Forensic Disciplines

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History of the San Diego County Sheriff's Crime Laboratory

Lab History Forensic services were first offered by the San Diego County Sheriff in 1950 out of a small building in Downtown San Diego. During the 50s the Department offered fingerprint examination services. In the early 60s the services expanded to photography and crime scene response, and by 1967, the first Criminalist (Forensic Scientist) was hired. The Department's forensics unit began performing examinations in the areas of blood and narcotics identification, shoe and tire impression examinations, firearm and tool marks, arson, and paint analysis. By 1970 the forensics unit employed twelve staff including three Criminalists. In the early 70s, the Department added advanced blood and semen identification techniques and hired a document examiner to analyze questioned documents.

In 1974, the Sheriff's Crime Laboratory moved to a new facility north of Downtown San Diego. At that time the Crime Lab was staffed by 16 civilian and sworn personnel and began offering toxicology and breath alcohol instrument certification services. The Sheriff’s Crime Laboratory continued to operate out of this building for the next 20 years.

In 1989, the County of San Diego acquired a 4-acre site in Kearny Mesa which housed the recently closed Clairemont Community Hospital. The hospital was remodeled and converted to the Sheriff's Crime Laboratory in 1995. The Sheriff's Crime Laboratory remained at this location for the next 23 years until moving to the new facility in 2018.

Bloodstain Pattern Analysis

Bloodstain pattern analysis is the application of scientific principles and techniques to the analysis of bloodstains found at crime scenes or observed on evidence submitted to the laboratory. It involves the recognition and study of the physical characteristics of bloodstains and patterns as a function of origin, flight paths, force, and sequence. The ultimate result can be a reconstruction of the chain of events involving bloodshed.

Things that can sometimes be determined from a Bloodstain Pattern Analysis include:

Minimum number of blows on a source of blood
Locations of areas of impact on blood
Directions of swings of bloody objects
Directions of movements of bloody objects
Relative positions of people and objects
Sequence of events
Who or what could or could not have been present, and
What actions could or could not have occurred in the:
Suspect’s statements
Victim’s statements
Witness’ statements

Bloodstain Pattern Analysts prefer to attend the scene. Training is available for law enforcement personnel who are not sure when to ask an expert to come to a scene. If you would like to arrange to have this training for your agency, please contact the Crime Laboratory.

Controlled Substances Analysis / Narcotics

Criminalists in the Controlled Substances Analysis Section identify controlled substances, as defined by Federal and California Law. Identification is completed using a variety of laboratory methods that range from basic wet chemistry, such as thin layer chromatography, to sophisticated instrumentation such as the Gas Chromatograph Mass Spectrometer (GCMS).

The Section primarily processes evidence submissions from the San Diego County Sheriff jurisdiction. Additionally, the Section processes evidence for other surrounding agencies without the forensic capabilities to process controlled substances. This includes National City, Chula Vista, La Mesa, and El Cajon. Occasionally, the Section helps with submissions from the Border Patrol, California Correction – RJ Donovan State Prison, ABC, US Department of Forestry, US Department of Fish and Wildlife, US Postal Inspector, the US Armed Forces, and Local Colleges and Universities, among others.

In addition to laboratory analysis and reports, Criminalists provide expert witness testimony on cases that have been processed by the Section and provide training in narcotics presumptive testing and proper handling and packaging of suspected controlled substances for law enforcement officers in the field.

Educational Requirements

In order to work in the Controlled Substances Analysis Section you must meet the following educational requirements outlined for the Criminalist position:

A bachelor's degree from an accredited U.S. college or university, or a certified foreign studies equivalency in chemistry, biology, or a closely related field, with completed course work consisting of at least eight (8) semester/twelve (12) quarter units of general chemistry.

Once hired, Criminalists in the Controlled Substances Analysis Section complete specialized in-house training on seized dugs and attend a number of Department of Justice sponsored courses on the analysis of drugs.

Interesting Facts

Learn about different types of controlled substances and how they are processed at this link, produced by the National Forensic Science and Technology Center and Florida International University: Forensic Science Simplified - Drugs.

Controlled Substances Analysis By The Numbers

Over 50% of the casework produced by the section is identified and reported as methamphetamine.

Dangerous opiates are still on the rise—the first quarter of 2020 brought a 200% increase in fentanyl.

Crime Scene Investigation

The Crime Scene Investigation (CSI) Section is the only field unit in the Sheriff’s Crime Laboratory that works hand in hand with investigators on the front line. They are responsible for examining crime scenes for physical evidence and helping to determine what may have occurred. The laboratory team is comprised of Criminalists and Forensic Evidence Technicians that document the conditions of a scene with an accurate depiction of the locations and relationships of evidence items. There are many techniques that can be used to document a scene including photography and 3D laser scanning. The Section preserves and collects the items for laboratory analysis by other sections within the Sheriff’s Crime Laboratory, but can also process items of evidence that are not movable with a variety of techniques, such as development of latent prints using dusting powders or the use of chemical enhancers to expose latent blood.

Forensic Evidence Technicians are trained in latent print development and are able to use their skills to process items on scene or in the laboratory for latent prints. Criminalists have expertise in bloodstain pattern and trajectory analysis that may aid in performing a reconstruction of the crime that occurred. The evidence collected from the scene is delivered to the Sheriff’s Crime Laboratory for forensic examination, and a report is prepared detailing the actions taken in the field. The purpose of the CSI Section is to help establish what occurred and to identify the responsible person. The ability to recognize and properly collect physical evidence is critical to solving violent crimes. The CSI Section works closely with Forensic Biology Criminalists and Latent Print Examiners to get evidence processed in a timely manner.

The services provided to the community are photography, videography, crime scene diagrams, evidence collection, latent print development, latent blood enhancement, bloodstain pattern analysis, trajectory determination, crime scene reconstruction, and expert testimony.

Educational Requirements

The ideal candidate for a CSI team member will be a knowledgeable worker who will communicate effectively, demonstrate ethical behavior, be a team player, have value and respect for others, and be supportive of change.

Each Criminalist meets the educational requirements to work as a Criminalist in one of the other forensic units in the Crime Laboratory. They share their duties between their primary assignment and being a member of the Crime Scene Team. Each team member receives comprehensive training in general scene techniques and documentation, bloodstain pattern and trajectory analysis, and crime scene reconstruction.

The Forensic Evidence Technician minimum qualifications are an Associate of Science degree from an accredited college or university, or a certified foreign studies equivalency and a community college certificate in Evidence Technology or equivalent, AND, one (1) year of experience in the identification, documentation, collection, preservation, and transportation of physical evidence which must include fingerprint processing, OR, two (2) years of full-time experience as an Evidence Technician in a law enforcement agency.

Interesting Facts

Bloodstain Pattern Analysis- some things the CSI Criminalist might be able to tell from evidence at the crime scene:

Minimum number of blows on a source of blood
Locations of areas of impact on blood
Directions of swings of bloody objects
Directions of movements of bloody objects
Relative positions of people and objects
Sequence of events
Who or what could or could not have been present, and
What actions could or could not have occurred in the:
Suspect’s statements
Victim’s statements
Witness’ statements

Learn about crime scene investigation, blood analysis, and the “CSI effect” at these links, produced by the National Forensic Science and Technology Center and Florida International University:

Firearms

The Firearms Section chiefly performs operability tests for firearms, firearm legality analysis, and comparisons of fired bullets and expended cartridge cases specific firearms that were used at the scene of a crime. Analysts receive an array of evidence, from firearms and expended cartridge cases to clothing from shooting victims in order to determine muzzle- to- target distance. Analysts use comparison microscopes to view and compare the minutia on cartridges and match them to specific firearms and/or other cartridges found at the crime scene. They also have an indoor shooting range and an entire firearm and ammunition reference collection at their disposal to compare and identify unknown evidence items. The Integrated Ballistic Identification System (IBIS) is used by analysts and technicians to import images of expended cartridges and potentially match them to firearm evidence from other cases. The Section also provides training to on-call Criminalists in firearms safety and bullet trajectory analysis as well as deputies and officers from other agencies on proper documentation of firearms.

Educational Requirements

In order to work in the Firearms Section you must meet the following educational requirements outlined for the Criminalist position.

Interesting Facts

The Sheriff’s Crime Laboratory’s firearm reference collection holds over 1500 firearms, and even that is just a small sample of the various firearm models in existence!
Firearms are often times inaccurately portrayed in movies and TV shows; firearms analysts are sure to point out these inaccuracies if you ever watch a film with them.
Firearms, like fingerprints, are unique in that they leave striations and markings on fired cartridge cases specific to the firearm used.
Learn about firearms at this link, produced by the National Forensic Science and Technology Center and Florida International University: Forensic Science Simplified – Firearms
Learn about firearms and ballistics at this link, produced by The Forensics Library: The Forensics Library - Firearms and Ballistics
Learn about a career in firearms and toolmark examination at this link, produced by CrimeSceneInvestigatorEdu: Firearms and Toolmark Examiner Careers

Interesting Cases

Firearms analysts are still, to this day, looking at evidence from the John F. Kennedy assassination to prove to skeptics that the single shooter explanation is valid.
The firearm evidence from both the Santana High School shooting in 2001 and the Poway Synagogue shooting in 2019 was evaluated by Criminalists at the San Diego County Sheriff Regional Crime Laboratory.

Firearms by the Numbers

The firearms section works on an average of 640 case requests every year.

Forensic Toxicology

The Forensic Toxicology Section is responsible for the analysis of antemortem fluid samples (from living individuals) to determine the ethanol, or drinking alcohol, concentration in the sample using a method called Headspace Gas Chromatography. The San Diego County Office of the Medical Examiner handles postmortem testing (samples from deceased individuals). The majority of the samples processed by Forensic Toxicology Criminalists are blood samples related to driving under the influence of alcohol and/or drugs (DUI/DUID) cases, but the Section also receives blood and urine samples involving other criminal offenses such as drug-facilitated Sexual Assaults and Homicides. The Section also analyzes jail-brews, or "pruno" samples, where inmates in San Diego jails and prisons create fermented liquids using a variety of fruits and a source of yeast. Suspect beverages related to the sale of alcohol to minors and other concoctions pertaining to license violations under the jurisdiction of the California Department of Alcoholic Beverage Control are also typically submitted to the Forensic Toxicology Section for analysis.

While not conducted in house at the Sheriff’s Crime Laboratory, many of the samples received by the Section require toxicological examination. The Forensic Toxicology Section serves as the hub for the shipment of blood and urine samples to the current vendor to perform that analysis.

The Section also manages the evidentiary breath testing program in the County of San Diego, providing calibration, maintenance, and technical support of the Intoximeters®, Inc. Intox EC/IR II instruments that are deployed to various law enforcement agencies in San Diego County to test subject's breath alcohol concentrations. Criminalists are also responsible for training new operators on the proper use of the instrument to conduct subject testing.

One of the Section's main responsibilities is to provide expert witness testimony on the analysis of alcohol in fluid samples, as well as the effects of alcohol on the human body as it relates to driving skills and performance at various blood or breath alcohol concentrations. Criminalists testify in Federal, State, Superior and Juvenile Courts, as well as in administrative hearings for license revocations by the Department of Motor Vehicles and the Alcoholic Beverage Control, and Military Court Martials and civil depositions to provide opinions and interpretations of the blood or breath test results obtained.

Educational Requirements

In order to work in the Forensic Toxicology Section you must meet the minimum educational requirements outlined for the Criminalist position:

Each Forensic Toxicology Criminalist receives comprehensive training in pharmacokinetics (the absorption, distribution, and elimination of alcohol in the human body), pharmacodynamics (the physical and mental effects of alcohol on the human body as it pertains to the ability to operate a motor vehicle safely), theory and operation of the instrumentation employed to determine alcohol content in blood and breath samples, and in the administration and interpretation of Standardized Field Sobriety Tests (SFSTs) used by law enforcement officers in the field when conducting a DUI/DUID investigation.

Coursework or background education in analytical chemistry and physiology/biomedical sciences is very helpful in this regard.

Interesting Facts

Did you know that the law in California for Driving Under the Influence (DUI) has two components? One component makes it illegal to drive with a BAC of 0.08 g/100mL or higher. The other component makes it illegal to drive while "under the influence" of alcohol, which can be at BAC levels below 0.08 g/100mL
Not all drinks are created equal! A "standard drink" in the industry is defined as a drink that contains 14 grams, or 0.6 fluid ounces, of pure ethanol.
The average BAC of the arrested drinking driver in San Diego County is 0.16 g/100mL, or TWICE the legal limit.
The most common BAC result from blood samples tested in San Diego County is 0.00 g/100mL. Many of these samples subsequently screen positive for various controlled substances and prescription drugs.
The highest BAC ever recorded at the Sheriff’s Crime Laboratory was 0.56 g/100mL (SEVEN TIMES the legal limit)
The average time a Criminalist at the Sheriff's Crime Laboratory is on the stand for alcohol interpretation testimony for a DUI case is approximately 2.5-3 hours
The longest time a Criminalist at the Sheriff's Crime Laboratory was on the stand for a DUI case, including direct exam by the DA and cross exam by the defense attorney, was approximately 9 hours
The Sheriff’s Crime Laboratory processes the alcohol and toxicology evidence for every law enforcement agency in San Diego County, with the exception of the San Diego Police Department who has their own Crime Lab. This includes Sheriff’s stations, California Highway Patrol, City Police Departments, University and Community College Police Departments, Military Police, and State Parks, to name a few!

National Highway Traffic Safety Administration

California Office of Traffic Safety

Drug-Impaired Driving

California Highway Patrol

Impaired Driver Enforcement Programs

Forensic Toxicology by the Numbers

Early Estimate of Motor Vehicle Traffic Fatalities in 2019 (May 2020)
Alcohol-Impaired Driving (December 2019)
Average weekly number of times expert testimony is provided by Criminalists: 4
Average annual number of blood/urine samples tested for alcohol concentration: 4600
Average annual number of breath samples tested for alcohol concentration: 4500
Average annual number of blood/urine samples sent for toxicology testing: 3400

Forensic Biology

The Forensic Biology Section is often referred to as the "DNA Section" because it uses DNA technology to help solve crimes. The Section is responsible for analysis of evidence from crimes against persons and property, with the purpose of identifying and individualizing biological materials found as part of that evidence. Commonly examined materials include blood, semen, saliva, tissues, and touched items. The Section has the capacity to identify body fluids, determine species of origin, and develop DNA profiles from evidentiary items. Forensic Biology Criminalists testify to these results in criminal trials.

The Section works closely with detectives investigating crimes. They also educate law enforcement and the public about their work and participate in community events and programs, such as the academy training of Sheriff's cadets, the county Sexual Assault Response Team training program, law enforcement training in biological evidence collection, and school presentations.

The San Diego Sheriff's Crime Laboratory is part of the Combined DNA Index System (CODIS), the national criminal DNA database. DNA profiles developed from evidence examined by the Forensic Biology Section are uploaded to CODIS, so that they may be searched against DNA profiles from convicted offenders, felony arrestees, and evidence profiles from other forensic laboratories in the system. CODIS reports matches between newly uploaded and previously entered profiles. The Forensic Biology Section communicates these matches to detectives, to provide investigative leads.

Educational Requirements

In order to work in the Forensic Biology Section you must meet the following educational requirements outlined for the Criminalist position:

Criminalists in the Forensic Biology Section must also meet the educational requirements outlined by the Quality Assurance Standards for Forensic DNA Testing Laboratories (FBI QAS) described by the FBI. This includes a total of 9 semester units (13.5 quarter units) combined for a class each in Molecular Biology, Biochemistry, and Genetics. A course in Statistics or Population Genetics is also required.

Interesting Facts

We share 99.9% of our DNA, that is what makes us human! That is how we all have two eyes, two ears, and a nose. That is how our bodies function and gives us characteristics like our eye and hair color. There is high variability in specific sections of the remaining 0.1% of our DNA, that is the portion of DNA used by Forensic Biology Criminalists.
You get half of your DNA from your biological mother and half of your DNA from your biological father.
No two people have the exact same DNA, except for identical twins.
All of your cells carry your DNA except red blood cells. Your red blood cells have the important job of carrying oxygen and they perform that job better if they don’t have a nucleus, where DNA is normally stored.
Learn about Forensic Biology and DNA processing at this link, a website produced by the National Forensic Science and Technology Center and Florida International University: Forensic Science Simplified - DNA.

Interesting Cases

The first known crime solved with the use of DNA technology occurred in the United Kingdom in 1987 – scientist Alec Jeffrey's was able to solve the homicide of a teenage girl utilizing early forensic DNA technology (The Blooding by Joseph Wambaugh is a book that covers the topic). The field has advanced exponentially in that time, in both sensitivity and specificity (Chemical Engineering News Article 17 Sept 2017 accessed 06/15/2020). One of the latest advances in the forensic DNA community is the ability to use Forensic Genetic Genealogy to solve crimes.

Forensic Genetic Genealogy combines DNA typing technology with traditional genealogy research to potentially identify unknown suspects for investigations that have typically gone cold. Ordinarily, the DNA analysis is completed by a private laboratory utilizing a DNA technology that the Sheriff's Department Crime Laboratory does not complete. The first case to garner national attention is often referred to as the "Golden State Killer" case (Harvard Science In the News 2 Sept 2018 accessed 06/15/2020). The alleged perpetrator of a multitude of both sexual assaults and homicides in Northern and Southern California in the 1970's and 1980's was apprehended in April of 2018 after investigators were able to piece together a suspect profile utilizing genetics and traditional genealogy research. The forensic DNA community is working on how to best utilize this important tool (Science Magazine Editorial 11 Oct 2019 accessed 06/15/2020).

Latent Print Development

The Latent Print Section consists of two sub-disciplines, Latent Print Analysis and Latent Print Development. The Latent Print Analysis Section is responsible for the examination of unknown and known prints that were collected from crime scenes. Using the ACE-V method it is the goal of the latent print examiner to analyze and compare prints to any subjects. If prints are recovered with no known subject(s), the prints may be searched in the Automated Fingerprint Identification System (AFIS).

The Latent Print Development Section is responsible for processing items of evidence that are recovered from crime scenes for latent fingerprints. Items are processed using both powder and chemical enhancement techniques. If latent prints are recovered from an item of evidence, the prints must be preserved by either physical means (ex: fingerprint tape and lift card) or through photography. An analyst in the latent print development section must have technical expertise in "sequential processing", which is understanding the order of latent print techniques to utilize depending on the substrate being processed. If an analyst does not follow proper sequential processing, they risk the potential destruction of latent print evidence. Latent prints do not always lend themselves to being physically preserved. In these instances, the fingerprint must be photographed. Without skillful knowledge of photography, the analyst will be unable to properly preserve the evidence.

In addition to analyzing and developing latent fingerprints, the section has a Crime Scene Investigation team. The primary duty is the collection of Major Case Prints from both living and deceased individuals. This specialized collection of known prints is subsequently used in the Crime Laboratory by Latent Print Examiners for comparison of latent print evidence recovered from Homicide and Death Investigation scenes. Other duties include identification of John & Jane Doe victims as well as the restoration of mummified, desiccated, or otherwise decomposed friction ridge skin.

Educational Requirements

In order to work in the Latent Print Section you must meet the following educational requirements outlined for the Latent Print Examiner position:

A bachelor's degree or higher from a U.S. accredited college or university, or a certified foreign studies equivalency in forensics, administration of justice, evidence technology, biology, chemistry, or a closely related field, which must have included one (1) year of internship with a law enforcement agency in latent print development or with a law enforcement agency analyzing fingerprints for identification; or,
An associate's degree from a U.S. accredited college or university, or a certified foreign studies equivalency in administration of justice, evidence technology, biology, chemistry, or a closely related field; and at least one (1) year of experience with a law enforcement agency in latent print development, and at least one (1) year of experience with a law enforcement agency in analyzing fingerprints for identification; or,
Four (4) years of experience with a law enforcement agency analyzing fingerprints for identification.

Interesting Facts

Are fingerprints inherited... are they more similar between family members than between strangers? The general shape or overall pattern of finger and palm prints can be inherited. Family members will often have similar patterns or designs (whorls, loops, etc.) on the same fingers of their hands. The tiny details in the fingerprint ridges, however, are not inherited and are different between all friction skin areas of individual people ... even between twins.
Why does a police officer touch your car tail light or bumper when they pull you over? To leave fingerprint and DNA evidence behind just in case something goes bad for them. This provides critical evidence so investigators can place the vehicle and its owner at the scene in case you try to flee.
Adermatoglyphia is a disease where people are born without fingerprints. It is exceedingly rare, affecting only four known extended families worldwide.
Identical twins are indistinguishable via DNA testing, but fingerprints can still tell them apart.
Do you have what it takes to be a latent print examiner? Check out this quiz from the National Institute of Standards and Technology : NIST Fingerprint Examiner Quiz

Interesting Cases

latent print drawing The Night Stalker

Richard Ramirez, the Night Stalker of Southern California in the 1980’s, was one of the first criminals to be apprehended by the use of the DOJ’s Automated Fingerprint Identification System.

Crime Museum – Richard Ramirez: The Night Stalker

Latent Print by the Numbers

Latent Print Development processes on average over 1200 items a year They produce over 3800 latent print cards and take over 8800 photographs during the processing of evidence for prints

Latent Print Examination

Educational Requirements

In order to work in the Latent Print Section you must meet the following educational requirements outlined for the Latent Print Examiner position:

A bachelor's degree or higher from a U.S. accredited college or university, or a certified foreign studies equivalency in forensics, administration of justice, evidence technology, biology, chemistry, or a closely related field, which must have included one (1) year of internship with a law enforcement agency in latent print development or with a law enforcement agency analyzing fingerprints for identification; or,
An associate's degree from a U.S. accredited college or university, or a certified foreign studies equivalency in administration of justice, evidence technology, biology, chemistry, or a closely related field; and at least one (1) year of experience with a law enforcement agency in latent print development, and at least one (1) year of experience with a law enforcement agency in analyzing fingerprints for identification; or,
Four (4) years of experience with a law enforcement agency analyzing fingerprints for identification.

Interesting Facts

Are fingerprints inherited... are they more similar between family members than between strangers? The general shape or overall pattern of finger and palm prints can be inherited. Family members will often have similar patterns or designs (whorls, loops, etc.) on the same fingers of their hands. The tiny details in the fingerprint ridges, however, are not inherited and are different between all friction skin areas of individual people ... even between twins.
Why does a police officer touch your car tail light or bumper when they pull you over? To leave fingerprint and DNA evidence behind just in case something goes bad for them. This provides critical evidence so investigators can place the vehicle and its owner at the scene in case you try to flee.
Adermatoglyphia is a disease where people are born without fingerprints. It is exceedingly rare, affecting only four known extended families worldwide.
Identical twins are indistinguishable via DNA testing, but fingerprints can still tell them apart.
Do you have what it takes to be a latent print examiner? Check out this quiz from the National Institute of Standards and Technology : NIST Fingerprint Examiner Quiz

Interesting Cases

latent print drawing The Night Stalker

Richard Ramirez, the Night Stalker of Southern California in the 1980’s, was one of the first criminals to be apprehended by the use of the DOJ’s Automated Fingerprint Identification System.

Crime Museum – Richard Ramirez: The Night Stalker

Latent Print by the Numbers

Latent Print Development processes on average over 1200 items a year They produce over 3800 latent print cards and take over 8800 photographs during the processing of evidence for prints

Questioned Document

The San Diego Sheriff's Forensic Document Examiners (FDE) examine evidence in cases involving jail mail, counterfeits, threats, wills, fraud, altered documents, and more. They are a non-destructive section that utilizes microscopes, illumination and filters, and static electricity to develop and examine characteristics of evidence that might not be seen by the unaided eye.

The responsibility of the FDE is to examine and compare documents to determine authenticity and/or authorship.

A document is anything that is relaying a message or serving as a record. A variety of items are submitted to the Questioned Document Section for examination and comparison. A wide variety of evidence can be analyzed including items such as purported counterfeit currency, a threat letter written on paper, or even a baseball bat.

Educational Requirements

In order to work in the Questioned Documents Section, you must meet the following educational requirements outlined for the Forensic Document Examiner position:

Four-year degree with at least two (2) college-level courses in the natural, physical, computer science or other closely related fields.
Completion of two-year apprenticeship training under a certified Forensic Document Examiner. The San Diego Sheriff's Department requires three years of apprenticeship training under a certified Forensic Document Examiner.

Interesting Facts

The human eye can only view the visible light portion of the electromagnetic spectrum. Visible light is viewed as the colors of the rainbow, white (the presence of all colors), and black (the absence of color).
The Video Spectral Comparator allows the FDE to examine documents outside the visible portion and into the ultraviolet and infrared portions of the electromagnetic spectrum.
Research has confirmed that with a sufficient amount of handwriting samples even the handwriting of twins, fraternal or identical and individuals of multiple births can be distinguished.
The indentations often made when writing in a notebook or on a stack of paper, can be developed and made readable by forensic document examiners several pages deep and several years later.
Qualified FDEs are able to distinguish naturally written signatures from those that appear to be simulated or forged.
Personality traits cannot be determined from a handwriting comparison.
The directionality of a pen stroke can be determined by striations in the ink.
In addition to paper, the Questioned Documents Section has examined handwriting on surfaces such as a Mylar balloon, a baseball bat, bathroom walls, a mirror, a sidewalk, and a garage door.
The ESDA (Electrostatic Detection Apparatus) develops indentations on paper.
The VSC (Video Spectral Comparator) uses lights and filters to differentiate inks, to "see through" correction fluid and ink obliterations, and to view security features such as: UV (ultra-violet) reactive security threads, fibers, and inks; IR (infrared) reactive fibers; watermarks; perforations; and holograms.

Interesting Cases

Jail mail with suspected drugs is turned into the Questioned Document section. If known writing for a suspect is also submitted the FDE can conduct a comparison to demine authorship. If no known writing is available for comparison the FDE can compare several pieces of mail to determine if they were written by one writer.

A threat letter is submitted with no suspect. The FDE can capture high resolution images of the writing for a later comparison. The FDE will also examine the letter for indented impressions that may link that item of evidence to others associated with this case (i.e. another letter and/or a notebook).

Lindbergh Kidnapping

In 1932, 20-month-old Charles Lindbergh Jr. was kidnapped from his nursery and a ransom note was left in his place. During this investigation a total of twelve (12) ransom notes were received by the Lindbergh family. In 1933 the FBI took over the case and determined the writer of the ransom notes to be German based on characteristics in the handwriting. In 1934 Bruno Richard Hauptmann was arrested after using a tracked gold certificate at a gas station. His handwriting was examined and compared to the Lindbergh Kidnapping ransom notes by numerous examiners. All the examiners were in agreement that Hauptmann was the writer of the ransom notes.

Angelo La Marca

In 1956, 1-month-old Peter Weinberger was kidnapped, and a ransom note was left behind. A second note was left at a failed drop-off attempt. It was determined that the ransom notes were the best evidence in the case. FBI handwriting experts found distinguishing characteristics in 16 letters in the notes. After searching through approximately 2 million official documents; a probation violation form for Angelo John LaMarca was found. This was compared to the ransom notes. After his arrest and being presented with the handwriting evidence, LaMarca confessed to the kidnapping. Further evidence was discovered in LaMarca's garage. This included a paper-pad that after examination was determined to have shared a common source with the second ransom note.

Zodiac Killer

The unsolved case of the Zodiac Killer involved handwriting examination. Beginning in 1969 as many as twenty (20) letters were received and believed to have been written by the Zodiac, the first of which were received on August 1st. Each of these first three letters contained one-third of a 408-symbol cryptogram, or code, which the Zodiac claimed would reveal his identity. On August 8th the cryptogram was decoded but the information did not contain the writer's identity. Several more letters were examined, some including more elaborate codes that have yet to be decoded. More than 9,000 handwriting samples including college applications and military records were examined by one well known handwriting examiner alone. Though there have been many suspects developed over the past 40 years, all have been ruled out through good detective work, DNA, fingerprints, or handwriting examinations. Will the mystery of the Zodiac Killer’s identity ever be solved?

Questioned Documents by the Numbers

The Questioned Documents Section processes hundreds of documents with the ESDA every year.
Between 2015 and 2019, the Questioned Documents Section examined 1,890 questioned documents and 248 questioned signatures.

Trace Evidence

The Trace Evidence Section analyzes a variety of evidence to determine whether an item can be connected to a person, place, or thing. Items Criminalists often analyze include hair fibers, manufactured fibers, paint fragments, ignitable or unidentified liquids, shoe and tire impressions, and explosives. Comparison of items is a foundation principle of the section's process. Criminalists use stereoscopes and comparison microscopes, Fourier- transform infrared spectroscopy, and Mass Spectroscopy to compare items to exemplars and ultimately find differences between items rather than similarities, contrary to popular belief. They also conduct physical matching of manufactured items; this is the reassembly of broken items according to fracture lines in order to prove pieces of an item were connected at some point in time. While the analyzed evidence cannot identify a suspect, it can be used to help detectives corroborate a sequence of events or eliminate a suspect from an investigation. The Trace Section trains Attorneys on arson case evaluation, and Forensic Evidence Technicians and Detectives on how to process crime scenes for trace evidence.

Educational Requirements

In order to work in the Trace Evidence Section you must meet the following educational requirements outlined for the Criminalist position.

A degree in chemistry is preferable, because chemical analysis of evidence is a large portion of the job.

Interesting Facts

Even though shoes are a mass produced item, shoe impressions can essentially act as a fingerprint in that the longer a person wears them, the more wear and tear they experience and become more unique and identifiable to a specific pair.
Most fires in arson cases are found to be started with gasoline.
Most criminals are so concerned about not leaving fingerprint and DNA evidence at a scene that they usually leave behind a plethora of trace evidence such as shoe prints and fibers from clothing and hair.
Learn about trace evidence at this link, produced by the National Forensic Science and Technology Center and Florida International University: Forensic Science Simplified - Trace
Learn about trace evidence at this link, produced by the New Jersey State Police: NJSP - Trace Evidence
Learn about a career as a trace evidence analyst at this link, produced by CrimeSceneInvestigatorEdu: Trace Evidence Analyst

Trace Evidence by the Numbers

The Trace Evidence section processes an estimated 8-10 cases every month. Analysis can be a lengthy process depending on the type of evidence being analyzed. For example, an unknown item, such as an ignitable liquid or a fiber, may take approximately a day to identify given that the laboratory has the proper reference materials to compare the item to. In contrast, a paint comparison can potentially take up to a month to complete due to the lengthy shaving process and chemical analysis of paint chips that the analysts receive.

Cal-ID

The California Identification System/Remote Access Network (Cal-ID/RAN) consists of a statewide network of equipment and procedures providing local law enforcement agencies direct access to local, state, and federal automated fingerprint, palm print, photo systems, and databases. It provides rapid identification of criminals booked into detention facilities and latent prints lifted from crime scenes.

18 cities throughout the County participate in the program
Funded through V.C. 9250.19

Livescans

Livescans throughout San Diego County Law Enforcement Agencies and Detention Facilities

Bluecheck Devices

Law enforcement officers utilize the fingerprinting device Bluecheck to help identify individuals when out in the field. With individual's fingerprint, correct first name and birthdate, an ID can be made. To use the device, the suspect places his two index fingers on the scanner. The digital image is run through San Diego's database, the state's Department of Justice database and the FBI database for a match.