Forensic Labs


INTRODUCTION

The Medical Examiner-Coroner (ME-C) Forensic Science Laboratory conducts a comprehensive scientific investigation into the cause and manner of any sudden, suspicious or violent death occurring in Los Angeles County.  The Laboratory performs analysis in four distinct forensic disciplines: Drug Chemistry, Toolmark Analysis in biological specimens, Toxicology, and Trace Evidence.  Each of these disciplines is accredited under the International Program by the nationally recognized American Society of Crime Laboratory Directors-Laboratory Accreditation Board (ASCLD-LAB).  Other important Laboratory sections include the Criminalistic Field Evidence response, Evidence Control, and Histology.

 

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

Lab Equipment         Miscellaneous test tubes

 


CRIMINALISTIC FIELD EVIDENCE

The Medical Examiner-Coroner's team of forensic scientists (a.k.a., criminalists) is on call 24 hours/day to respond to crime scenes where the following may be necessary:

  • Ligature Removal:  In cases where a victim has been tied or restricted in any fashion (shoe laces, duct-tape, ropes, electrical cords, etc.).
  • Sexual Assault Evidence Collection:  In cases where rape or sexual activity 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 are skeletonized.  An anthropologist will work in conjunction with the forensic scientist in the recovery of human remains.
  • Physical Evidence Collection:  In cases where trace material, including hairs, fibers, vegetation matter, or stains are present on the decedent.
  • Arson Evidence Collection:  In cases where an accelerant may have been used to initiate a fire, 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 CONTROL

The Evidence Control section is the central point for the receipt and management of evidence generated from Medical Examiner-Coroner cases.  The section provides quality service to contributors of evidence and acts as a liaison between the Department and the many law enforcement agencies within the County. The section manages evidence collected by Department personnel such as exemplars, projectiles, decedent clothing, drug paraphernalia, and trace material from submission to release or final disposition.  Further, the section provides education and guidance on packaging, transportation and storage of evidence while maintaining chain of custody throughout. To request the release of evidence, crime laboratory or handling, agency personnel should contact 323-343-0501.

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-Coroner cases and offers GSR analysis to outside investigating agencies for a fee. For information on requesting GSR analysis, click here.

HISTOLOGY

Histology or Histopathology is the examination of tissues from the body under a microscope to detect the signs and characteristics of disease.  The Laboratory section provides histological support for Pathologists or Deputy Medical Examiners in obtaining hematoxylin and eosin (H&E) stains, special stains, and immunochemistry stains of biological tissue.  The stained slides can provide information such as:

  • Cellular variation in tissue
  • Aging of injuries or degree of injury
  • Diagnosis of diseases, including cancer
  • Presence of bacteria, medical disorders, and toxins, like asbestos
  • By-products of some drugs can be observed as 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

The Department of Medical Examiner-Coroner performs postmortem and human performance (antemortem) toxicology.  Postmortem toxicology analyzes biological specimens collected at autopsy for the presence of drugs, toxins, and poisons to help determine cause and manner of death. Following autopsy, medical examiners can request specific drug panels to include alcohol, drugs of abuse and various pharmaceutical medications.

Human performance (antemortem) toxicology analyzes blood or urine from living persons for the presence of drugs that could cause an adverse reaction on the body or influence behavior possibly leading to prosecution in a court of law. The Department typically receives human performance requests from law enforcement agencies (e.g. DUID).