FBI Handbook of Crime Scene Forensics

The successful investigation and prosecution of crimes require, in most cases, the collection, preservation, and forensic analysis of evidence. Forensic analysis of evidence is often crucial to determinations of guilt or innocence.

The FBI has one of the largest and most comprehensive forensic laboratories in the world, and the FBI Laboratory is accredited by the American Society of Crime Laboratory Directors/ Laboratory Accreditation Board. The forensic services of the FBI Laboratory Division and the Operational Technology Division are available to the following:

• FBI field offices and legal attachés.
  
• U.S. attorneys, military tribunals, and other federal agencies for civil and criminal matters.
  
• State, county, and municipal law enforcement agencies in the United States and territorial possessions for criminal matters.
  

All forensic services, including expert witness testimonies, are rendered free of cost; however, the following limitations apply:

• No examination will be conducted on evidence that has been previously subjected to the same type of examination. Exceptions may be granted when there are reasons for a reexamination. These reasons should be explained in separate letters from the director of the laboratory that conducted the original examination, the prosecuting attorney, and the investigating agency.
  
• No request for an examination will be accepted from laboratories having the capability of conducting the examination. Exceptions may be granted upon approval of the FBI Laboratory Director or a designee.
  
• No testimony will be furnished if testimony on the same subject and in the same case is provided for the prosecution by another expert.
  
• No request for an examination will be accepted from a nonfederal law enforcement agency in civil matters.
  

In addition, when submitting evidence to the FBI Laboratory, contributors acknowledge the following:

• FBI examiners will choose appropriate technical processes to address the contributor’s request for examination.
  
• Depending on the caseload of the Laboratory and the needs of the contributor, evidence examinations may be subcontracted.
  
• An FBI Laboratory Report of Examination may contain the opinions and/or interpretations of the examiner(s) who issued the report.
  

The FBI accepts evidence related to all crimes under investigation by FBI field offices; however, it accepts from state and local law enforcement agencies only evidence related to violent crime investigations. The FBI does not routinely accept evidence from state and local law enforcement agencies in cases involving property crimes unless there was personal injury or intent to cause personal injury. These guidelines help to ensure that the FBI continues to provide timely forensic assistance to law enforcement agencies investigating crimes of violence or threatened violence. Additional restrictions may be imposed on case acceptance to achieve this goal.

At the discretion of the FBI Laboratory Director or a designee, the FBI may accept evidence from property crime cases. Such exceptions will be considered on a case-by-case basis and should not be regarded as setting a precedent for future case acceptance. All accepted cases will be afforded the full range of forensic services provided by the FBI.

The following are examples of property crimes that are not routinely accepted for examinations:

• Arson of unoccupied residential and commercial buildings and property.
  
• Explosive incidents and hoaxes targeting unoccupied residential and commercial buildings and property.
  
• Vandalism and malicious mischief directed toward residential or commercial buildings and property.
  
• Nonfatal traffic accidents involving speedometer and headlight examinations except in cases involving law enforcement and government officials.
  
• Hit-and-run automobile accidents not involving personal injury.
  
• Automobile theft, except automobile theft rings or carjackings.
  
• Breaking and entering.
  
• Burglary.
  
• Minor theft (under $100,000).
  

Minor fraud (under $100,000).

All requests for evidence examinations should be in writing, on agency letterhead, and addressed to the FBI Laboratory Evidence Control Unit, unless otherwise indicated in the
Examinations
section.

Do not submit multiple cases under a single communication. Each case should be submitted with a separate communication and packaged separately.

All international law enforcement agency/ police requests should be coordinated through the appropriate FBI legal attaché (LEGAT). LEGATs should fax the request to the Evidence Control Unit, 703-632-8334, prior to submitting any evidence to the Laboratory. Questions concerning international submissions should be directed to 703-632-8360.

Requests for evidence examinations must contain the following information:

• The submitting contact person’s name, agency, address, and telephone number.
  
• Previous case-identification numbers, evidence submissions, and communications relating to the case.
  
• Description of the nature and the basic facts of the case as they pertain to evidence examinations.
  
• The name(s) of and descriptive data about the individual(s) involved (subject, suspect, victim, or a combination of those categories) and the agency-assigned case-identification number.
  
• The name of the prosecutor assigned, if available.
  
• A list of the evidence being submitted “herewith” (enclosed) or “under separate cover.”
  
  • Herewith
    is limited to small items of evidence that are not endangered by transmitting in an envelope. Write on the envelope before placing evidence inside to avoid damaging or altering the evidence. The written communication should state: “
    Submitted herewith are the following items of evidence
    .”
    
  • Separate cover
    is used to ship numerous or bulky items of evidence. Include a copy of the communication requesting the examinations. The written communication should state: “
    Submitted under separate cover by [list the method of shipment] are the following items of evidence
    .”
    
• What type(s) of examination(s) is/are requested.
  
• Where the evidence should be returned and where the Laboratory report should be sent. A street address must be included.
  
• A statement if the evidence was previously examined, if there is local controversy, or if other law enforcement agencies have an interest in the case.
  

• Prior to packaging and shipping evidence, call the pertinent unit for specific instructions.
  
• Take precautions to preserve the evidence.
  
• Wrap and seal each item of evidence separately to avoid contamination.
  
• Place the evidence in a clean, dry, and previously unused inner container.
  
• Seal the inner container with tamper-evident or filament tape.
  
• Affix EVIDENCE and BIOHAZARD labels, if appropriate, on the inner container. If any of the evidence needs to be examined for latent prints, affix a LATENT label on the inner container.
  
• Affix the evidence examination request and all case information between the inner and outer containers.
  
• Place the sealed inner container in a clean, dry, and previously unused outer container with clean packing materials. Do not use loose Styrofoam.
  
• Completely seal the outer container so that tampering with the container would be evident.
  
• All
  shipments of suspected or onfirmed hazardous materials
  must comply with U.S. Department of Transportation and International Air Transport Association regulations. Title 49 of the Code of Federal Regulations (CFR) lists specific requirements that must be observed when preparing hazardous materials for shipment by air, land, or sea. In addition, the International Air Transport Association annually publishes
  Dangerous Goods Regulations
  detailing how to prepare and package shipments for air transportation.
  
• Title 49 CFR 172.101 provides a Hazardous Materials Table that identifies items considered hazardous for the purpose of transportation. Title 49 CFR 172.101 also addresses special provisions for certain materials, hazardous materials communications, emergency response information, and training requirements for shippers. A trained and qualified evidence technician must assist with the typing, labeling, packaging, and shipping of all hazardous materials.
  

U.S. Department of Transportation regulations and the following guidelines must be followed when shipping live ammunition:

• Package and ship ammunition separately from firearm(s).
  
• The outside of the container must be labeled “ORM-D, CARTRIDGES, SMALL ARMS.”
  
• The Declaration of Dangerous Goods must include the number of packages and the gross weight in grams of the completed packages.
  

• Unless otherwise indicated in the
  Examinations
  section, address the outer container as follows:
  

  EVIDENCE CONTROL UNIT
  LABORATORY DIVISION
  FEDERAL BUREAU OF INVESTIGATION
  2501 INVESTIGATION PARKWAY
  QUANTICO VA 22135
  

• Ship evidence by U.S. Postal Service Registered Mail, UPS, or FedEx. Record the method of shipment and the tracking number(s) on the chain-of-custody form.
  

Examinations may determine the type of abrasive material used to sabotage engines or machinery.

Questions concerning abrasives evidence should be directed to 703-632-8441.
Follow the evidence submission directions, including
Requesting Evidence Examinations
and
Packaging and Shipping Evidence
.

• Employ personnel familiar with the operations and mechanics of engines and machinery to recover abrasives.
  
• Abrasives settle in oil and fuel. Submit the oil and fuel from the engine pump and/or filters.
  
• Abrasives embed in bearings and other parts. Submit the bearings and other parts.
  
• Submit abrasives in heat-sealed or resealable plastic bags or paint cans. Do not use paper or glass containers.
  

Adhesives, caulks, and sealants can be compared by color and chemical composition with suspected sources. The source and manufacturer of adhesives, caulks, and sealants cannot be determined by compositional analysis.

Questions concerning adhesive, caulk, and sealant evidence should be directed to 703-632-8441
. Follow the evidence submission directions, including
Requesting Evidence Examinations
and
Packaging and Shipping Evidence
.

• When possible, submit the item to which the adhesive, caulk, or sealant is adhered. If this is not possible, remove a sample of the material with a clean, sharp instrument and transfer it to a resealable plastic bag or leakproof container such as a film canister or plastic pill bottle.
  
• Submit a suspected source. Package separately.
  

Anthropological examinations can determine whether something is a bone and, if so, whether it is human or animal in origin. Race, sex, approximate height and stature, and approximate age at death often can be determined from human remains. Damage to bone such as cuts, bluntforce trauma, and bullet holes also may be examined. Personal identifications can be made by comparing X-rays of a known individual with skeletal remains.

Anthropological examinations usually are conducted on bones sent to the Laboratory for DNA analysis or facial reproductions.

Questions concerning anthropological evidence should be directed to 703-632-8449
. Follow the evidence submission directions, including
Requesting Evidence Examinations
and
Packaging and Shipping Evidence
.

• Clean and air-dry bones, if possible. Pack in paper bags and wrap in protective material such as Bubble Wrap or paper. If tissue is present on the skeletal material, refrigerate until mailing, and then ship in a Styrofoam cooler.
  
• Collect insect samples found on the remains in leakproof containers such as film canisters or plastic pill bottles. Call the Laboratory at
  703-632-8449
  for additional instructions.
  

Submit medical records and X-rays, if possible.

Arson examinations can determine the presence of ignitable liquids introduced to a fire scene. Examinations of debris recovered from scenes can identify gasoline, fuel oils, and speciality solvents. Examinations generally cannot identify specific brands.

Search at questioned arson scenes for the following items: candles, cigarettes, matchbooks, Molotov cocktails, fused chemical masses, or any electronic or mechanical devices an arsonist may have used. Also search for burn trails on cloth or paper, burn trails on carpeted or hardwood floors, and the removal of personal property or commercial inventory.

Questions concerning arson evidence should be directed to 703-632-7641.
Follow the evidence submission directions, including
Requesting Evidence Examinations
and
Packaging and Shipping Evidence
.

Ignitable liquids are volatile and easily lost through evaporation. Preserve evidence in airtight containers such as metal cans, glass jars, or heat-sealed plastic bags approved for fire debris. Do not fill the containers to the top. Pack to prevent breakage.

Audio examinations are conducted by the FBI’s Operational Technology Division (OTD), Digital Evidence Laboratory (DEL), Forensic Audio, Video, and Image Analysis Unit (FAVIAU). The OTD DEL has different acceptance criteria and a different physical address than the FBI Laboratory, as described below.

Bank dye packs contain dye to stain money and clothing and tear gas to disorient a robber. Items such as money and clothing can be analyzed for the presence of bank security dye and tear gas.

Questions concerning bank security dye evidence should be directed to 703-632-8441.
Follow the evidence submission directions, including
Requesting Evidence Examinations
and
Packaging and Shipping Evidence
.

• Only evidence with visible red or pink stains will be examined.
  
• Do not submit large stained evidence (e.g., car seats). When possible, cut a small sample of the stained area and submit in a heat-sealed or resealable plastic bag. Collect an unstained control sample, package separately, and submit it with the dye-stained evidence. When cutting is not possible, transfer questioned stains by rubbing with a clean (dry or wet with alcohol) cotton swab. Use an unstained swab as a control. Air-dry the swab and pack in a heat-sealed or resealable plastic bag.
  

Examinations can compare building materials such as brick, mortar, plaster, stucco, cement, and concrete.

Questions concerning building materials evidence should be directed to 703-632-8449
. Follow the evidence submission directions, including
Requesting Evidence Examinations
and
Packaging and Shipping Evidence
.

• When building materials are penetrated or damaged, debris can adhere to people, clothing, tools, bags, and stolen items and can transfer to vehicles. If possible, submit the evidence to the Laboratory for examiners to remove the debris. Package each item of evidence in a separate paper bag. Do not process tools for latent prints.
  
• Collect known samples from the penetrated or damaged areas.
  
• Ship known and questioned debris separately to avoid contamination. Submit known and questioned debris in leakproof containers such as film canisters or plastic pill bottles. Do not use paper or glass containers. Pack to keep lumps intact.
  

Elemental analysis of bullet jackets can be done when a bullet has fragmented so that individual pieces cannot be used for comparison with test-fired ammunition from a firearm or in the absence of a firearm or the lead component of the bullet. This analysis may be helpful when there are multiple shooters and types of jacketed ammunition. Alloy classification can differentiate among bullet jacket alloys of different manufacturers or among the bullet jacket alloys in manufacturers’ production lines.

Questions concerning bullet jacket alloy examinations should be directed to 703-632-8441.
Follow the evidence submission directions, including
Requesting Evidence Examinations
and
Packaging and Shipping Evidence.

• Ammunition components such as bullets, cartridge cases, and shotshell casings can be sent via Registered Mail through the U.S. Postal Service. Evidence must be packaged separately with the date, time, location, collector’s name, case number, and evidence number written on the container.
  
• U.S. Department of Transportation regulations and the following guidelines must be followed when shipping live ammunition:
  
  • Package and ship ammunition separately from firearm(s).
    
  • The outside of the container must be labeled “ORM-D, CARTRIDGES, SMALL ARMS.”
    
  • The Declaration of Dangerous Goods must include the number of package(s) and the gross weight in grams of the completed package(s).
    
• Do not mark bullets, cartridges, cartridge cases, shotshells, or shotshell casings. The date, time, location, collector’s name, case number, and evidence number must be on the container.
  

General unknowns include powders, liquids, and stains that are of indeterminate origin or cannot be readily classified. Full identification of an unknown may not always be possible; however, general classification of a substance is usually achievable.

When comparison samples are available, it may be possible to comment regarding the consistency of the unknown substance compared with a known sample.

Call the Laboratory at 703-632-8441 prior to submitting general unknowns to ensure that the evidence will be accepted for examination.
The communication accompanying the evidence must reference the telephone conversation accepting the evidence.

Questions concerning examinations of general unknowns should be directed to 703-632-8441.
Follow the evidence submission directions, including
Requesting Evidence Examinations
and
Packaging and Shipping Evidence
.

• Submit powder and liquid samples in leakproof containers.
  

Do not submit large stained evidence. When possible, cut a small sample of the stained area and submit in a heat-sealed or resealable plastic bag. Collect an unstained control sample, package separately, and submit it with the stained evidence. When cutting is not possible, transfer questioned stains by rubbing with a clean (dry or wet with alcohol) cotton swab. Use an unstained swab as a control. Air-dry the swab and pack in a heat-sealed or resealable plastic bag.