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Forensic Labs

The Los Angeles County Department of Medical Examiner Forensic Sciences Laboratories Division is responsible for the identification, collection, preservation, and analysis of physical and medical evidence associated with Medical Examiner’s cases. Our mission is to conduct a comprehensive scientific investigation into the cause and manner of any death within the Medical Examiner’s jurisdiction. This is accomplished through the chemical and instrumental analysis of physical and medical evidence.

Our goal is to provide our medical examiners, families of decedents, outside investigating agencies, and the judicial system with timely, accurate, and advanced forensic analyses; and to provide expert interpretation of these analyses through testimony and deposition. The laboratories division includes the following: Toxicology, Histology, Human Genomics Unit/DNA, Scanning Electron Microscope lab (includes gunshot residue and toolmark analysis), Field Criminalistics and Evidence Control. Additionally, the Forensic Sciences Laboratories Division’s Toxicology, Drug Chemistry, Human Genomics/DNA, and Scanning Electron Microscopy (gunshot residue and toolmark analysis) testing are accredited by ANAB (ANSI National Accreditation Board) in the field of Forensic Testing per accreditation standards set forth in ISO/IEC 17025:2017, ANAB Forensic Testing & Calibration AR 3125:2019, and FBI Quality Assurance Standards for Forensic DNA Testing Laboratories: 2020. Our forensic blood alcohol testing program is licensed by the State of California (Title 17).

For more information on additional testing, interagency assists and other requests.

Additional Laboratory Requests

Criminalistic Field Evidence

Our teams of specially-trained criminalists are on call 24 hours per day to respond to crime scenes for the proper documentation, collection and preservation of physical evidence. Such scenes may include:

Ligature removal: In cases where a victim has been tied and/or restricted in any fashion.
Sexual assault evidence collection: In cases where rape or any sexual misconduct/assault is suspected.
Entomology evidence collection: In cases where decomposition of the body has progressed to a state that insect activity is present.
Excavation: In cases where decedents have been buried or skeletonized. An anthropologist will work in conjunction with the criminalist in the recovery of human remains.
Physical evidence collection: In cases where trace material including hairs, fibers, vegetative matter, or stains are present on the decedent.
Arson evidence collection: In cases where an accelerant may have been used to initiate a fire, the decedent’s clothing and surrounding evidence will be collected and packaged appropriately.

Drug Chemistry

Criminalists in the Drug Chemistry Section analyze materials for the presence of controlled substances such as cocaine, methamphetamine, marijuana, bath salts and synthetic cannabinoids. These controlled substances may be present in powders, solid materials, liquids, plant material, mushrooms, blotter paper, baby bottles, or food items collected at a death scene. Analyses may also include tablets, pills or drug residue collected at autopsy from decedents’ orifices, gastric and intestinal contents. Lastly, the section examines pharmaceutical preparations in the form of tablets, capsules, injectables and transdermal patches.

Evidence Unit

Our evidence unit is responsible for maintaining the integrity and chain-of-custody for all evidence collected from Medical Examiner cases. The unit maintains evidence collected by Department personnel such as projectiles, decedent clothing, drug paraphernalia, and trace material from submission to release or final disposition. The evidence unit provides quality service to department personnel and the many law enforcement agencies within LA county and outside the county. Additionally, the unit provides education and guidance on the collection, packaging, and proper chain of custody as needed.

Trace Evidence - Gunshot Residue Analysis

Gunshot Residue (GSR) originates from the discharge of a cartridge, typically from a firearm. The residue can contain particulate from the bullet jacket, if present, cartridge case, gun powder, primer, and the firearm itself. The portion of the residue that is discoverable with a scanning electron microscope fitted with an x-ray spectrometer is the primer material.

The Scanning Electron Microscopy Laboratory (SEM Lab) performs GSR Analysis on samples collected from Medical Examiner cases and offers GSR analysis to outside investigating agencies for a fee. For information on requesting GSR analysis, click Additional Laboratory Request.

Histology

This laboratory facilitates the preparation of gross tissue specimens for microscopic examination by the medical staff. This includes hematoxylin and eosin stains, special stains, and immuno-histochemical stains. Through the microscopic examination of tissue, our medical examiners can determine information such as:

Aging of injuries or degree of injury
Diagnosis of diseases, including cancers
Evaluate cellular variation in tissue
Identify the presence of bacterial infections/diseases, medical disorders, and toxins
Detection of by-products of some drugs as seen by crystalline structures

Toolmark Analysis in Biological Specimens

Toolmark analysis involves the evaluation of trauma in biological material collected from decedents and the comparison of the trauma with submitted suspect tools. Analysis can include the following: reconstruction of skeletal material, macro and micro photography, measurements, and test marks. The Laboratory has conducted this type of analysis for over 30 years for Los Angeles County and has acquired an extensive reference collection in bone exhibiting a wide range of trauma. Additionally, toolmark analyses and consultation are available to agencies outside of Los Angeles County.

Toxicology

Using advanced instrumentation and methods, the toxicology laboratory conducts chemical and instrumental analysis on post-mortem specimens collected at autopsy to determine the extent to which drugs may have contributed to a death. Alcohol, drugs of abuse and various pharmaceutical medications are analyzed through sensitive and specific methodologies. Evidence that may have been submitted with a case such as powders, tablets, plant material, blotter paper, liquids, food items, and/or other materials collected at a death scene can be analyzed in the laboratory using drug chemistry techniques. These analyses are requested by the medical examiner on an “as-needed” basis.

The laboratory’s experienced forensic toxicologists offer expert drug interpretation that assists the medical examiners in answering questions like:

What drug was taken?
How much and when was the drug taken?
Did the drug contribute to the cause and/or manner of death?
Was the drug use consistent with therapeutic administration, or was it abuse?
If the death is due to a drug overdose, was it intentional or accidental?

The Toxicology laboratory results, in conjunction with investigative and medical reports, help medical examiners reach a final determination for the cause and manner of death.

Human Genomics Unit/DNA

The Human Genomics Unit conducts DNA analysis for the identification of human remains, and in 2019, will provide genetic analysis to assist our medical examiners in cause of death investigations. These services are consistent with our mission statement to inquire into and determine the circumstances, manner, and cause of all violent, sudden, or unusual deaths occurring within Los Angeles County.

While we perform kinship testing and genetic testing for our medical examiners, we do not provide paternity and maternity testing or genetic testing as a service to the relatives of a decedent. Instead, the HGU will provide a decedent’s reference sample to an outside DNA testing laboratory for a processing/handling fee at the request of the next of kin of the decedent.

Glossary of Terms

Autopsy

also known as a post-mortem examination, necropsy (particularly as to non-human bodies), autopsia cadaverum, or obduction — is a highly specialized surgical procedure that consists of a thorough examination of a corpse to determine the cause and manner of death and to evaluate any disease or injury that may be present. It is usually performed by a specialized medical doctor called a pathologist.

Biological specimens

blood, sections of organs, vitreous, bile, and urine.

Cause of death

an injury or disease that ultimately leads to death of the individual, generally determined by medical examiners or coroners.

Certificate of Religious Belief

in California, in order to execute a certificate of religious belief, a person must be 18 years of age or older and must state in clear and unambiguous language that any postmortem anatomical dissection or that specified procedures would violate the religious convictions of the person. The certificate must be signed and dated by the person in the presence of at least two witnesses. Each witness must also sign the certificate and must print on the certificate his or her name and residence address. California law allows the state to override religious objection if the coroner "has a reasonable suspicion that the death was caused by the criminal act of another or by a contagious disease constituting a public health hazard."

Chain of custody

a method of keeping track of who has handled a piece of evidence and when.

County Disposition

The County of Los Angeles will cremate the remains of a decedent and hold the cremains (ashes) for a period of time (about 3 years) before the ashes are interred in a common gravesite at the LA County Cemetery.

Decomposition

the disintegration of body tissues after death.

DME

Department of Medical Examiner

Evidence

any physical items such as bullets, hairs, fibers, biological fluids, etc., documents and statements that are included in a legal investigation for the jury’s or judge’s consideration in the determination of an individual’s guilt or innocence.

Forensic pathologist

A medical doctor who specializes in the sub-specialty of pathology that focuses on determining the cause of death by examining a corpse. The autopsy is performed by the pathologist usually during the investigation of criminal law cases and civil law cases in some jurisdictions.

Forensic Science

Forensic Science is the application of all forms of science to aid legal investigations.

Indigency

The lack of ability to pay as a legal reason for having certain required fees waived; being declared eligible for free services.

Manner of death

is how the death came about. Natural - due entirely (or nearly so) to natural disease processes. Homicide - due to a volitional act of another person. Suicide - due to injury that occurred with the intent to induce self-harm or cause one’s own death. Accident - due to injury when there is no evidence of intent to harm. Undetermined - inadequate information regarding the circumstances of death to determine manner; example: individual found unconscious with massive subdural hemorrhage; in the absence of information on the events leading up to death, it is impossible to determine if the hemorrhage is due to accidental fall, homicidal violence, etc.

Medical examiner

is a medically qualified forensic pathologist and government official whose duty is to investigate deaths and injuries that occur under unusual or suspicious circumstances, to perform post-mortem examinations, and in some jurisdictions to initiate inquests.

Medicolegal Autopsy

a medicolegal autopsy is done with the possibility of litigation in mind. The autopsy is designed to determine the cause of death, properly document findings, and collect evidence. A primary objective is to try to reconstruct the circumstances and events that led to the death so that a mode (natural, accident, suicide, homicide, or undetermined) can be established. A medicolegal autopsy differs from a hospital autopsy. A hospital autopsy is designed to confirm a known or suspected disease and gain further knowledge of the disease. The emphasis is placed on the gross and microscopic examination of internal organs. In a medicolegal autopsy the emphasis is shifted to the external examination and the description of external and associated internal injuries. Microscopic examination is done only when indicated. Information about identification of the remains, time of death, evidence of drug use, age of injuries, etc., becomes important and must be recorded carefully. It is imperative that findings be recorded clearly and objectively. Any forensic pathologist should be able to interpret the findings years later without difficulty. The forensic autopsy protocol must be standardized and reproducible.

Next of Kin

aNearest relative: if married, the spouse, if no spouse then adult children, or surviving parents, or blood relative, according to California State Law, unless otherwise specified in a legal document.

Toxicology

or postmortem (after death) toxicology analyzes biological specimens collected at autopsy for the presence of drugs, toxins, and poisons to help determine cause and manner of death.