FBI Handbook of Crime Scene Forensics (2 page)

Read FBI Handbook of Crime Scene Forensics Online

Authors: Federal Bureau of Investigation

Tags: #Business & Economics, #Infrastructure, #Social Science, #General, #True Crime, #Murder

Controlled Substance Examinations

Controlled substance examinations can establish trace-drug presence, identity, and quantity.

Bulk Drugs

The Laboratory limits the quantity of bulk drugs that it will analyze. Quantities exceeding 100 grams of suspected marijuana or 10 grams of all other suspected drugs including cocaine, methamphetamine, and heroin will be returned unanalyzed. The Laboratory usually analyzes only drugs seized in federal investigations.

Drug Residue

Requests for drug residue examinations on evidence will be accepted only when the evidence is properly packaged to avoid contamination. Drug residue examinations of currency are performed only on a limited basis.

Call the Laboratory at 703-632-8441 prior to submitting drugs or currency 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 controlled substance evidence should be directed to 703-632-8441.
Follow the evidence submission directions, including
Requesting Evidence Examinations
and
Packaging and Shipping Evidence
.

  • Submit evidence in separate heat-sealed or resealable plastic bags.
  • Fold clothing to preserve trace evidence.
  • Do not submit used drug field-test kits with evidence.
Crime Scene Surveys, Documentation, and Reconstruction

Visual information specialists receive data from the field or travel to the field to collect it. They then use the data to prepare two- and three-dimensional digital or physical crime scene reconstructions as well as computer animations or models that depict bullet trajectory, line-of-sight analysis, and vehicular-, human-, or objectmovement analysis.

Questions concerning crime scene surveys, documentation, and reconstruction should be directed to 703-632-8194.

Cryptanalysis and Racketeering Record Examinations
Cryptanalysis

Cryptanalysis examinations involve the analysis of encoded and enciphered documents used by terrorists, foreign intelligence agents, violent criminals, street and prison gangs, and organized crime groups. Encrypted documents may be faxed or e-mailed for immediate decryption. Call
703-632-7356
or
703-632-7334
for contact information.

Drug Records

Drug records are examined to determine the overall scope of the businesses, including the hierarchy, type of drugs distributed, gross sales, gross or net weights or quantities, price structures, and other pertinent information.

Gambling

Gambling examinations include the interpretation of records from sports and horse bookmaking businesses, Internet gambling operations, numbers or lottery operations, and other gambling businesses.

Loan-Sharking

Loan-sharking records are examined to determine the amounts of the loans, amounts paid in interest and principal, number of loans, and interest rates.

Money Laundering

Money-laundering records are examined to determine the scope of the operations, the amounts laundered, how the funds were laundered, and any other illegal activities.

Prostitution

Prostitution records are examined to determine the scope of the businesses, including the number of employees and their roles, gross and net revenues, and other financial and organizational information.

Questions concerning cryptanalysis and racketeering record evidence should be directed to 703-632-7356 or 703-632-7334.
Follow the evidence submission directions, including
Requesting Evidence Examinations
and
Packaging and Shipping Evidence
.

Demonstrative Evidence

Visual information specialists prepare a wide array of demonstrative evidence for investigative and prosecutorial purposes. These items include charts, maps, diagrams, illustrations, and animated and digitally interactive presentations.

Questions concerning demonstrative evidence should be directed to 703-632-8194.

DNA Examinations

Deoxyribonucleic acid (DNA) is analyzed in body-fluid stains and other biological tissues recovered from items of evidence. The results of DNA testing on evidence samples are compared with the results of DNA analysis of reference samples collected from known individuals. Such analyses can associate victims and suspects with each other, with evidence items, or with a crime scene. There are two types of DNA used in forensic analyses. Nuclear DNA (nDNA) is the more discriminating of the two types and is typically analyzed in evidence containing blood, semen, saliva, body tissue, and hairs that have tissue at their root ends. The power of nDNA testing done by the DNA Analysis Unit I (DNAUI) lies in its ability to potentially identify an individual as being the source of the DNA obtained from an evidence item to a reasonable degree of scientific certainty, as well as the definitive power of exclusion. Additionally, where appropriate, the DNA-typing results from evidence items (including items related to missing persons) examined in the DNAUI may be uploaded into the Combined DNA Index System (CODIS) database.

Mitochondrial DNA (mtDNA) is typically analyzed in evidence containing naturally shed hairs, hair fragments, bones, and teeth. Typically, these items contain low concentrations of degraded DNA, making them unsuitable for nDNA examinations. The high sensitivity of mtDNA analysis allows scientists to obtain information from old items of evidence associated with cold cases, samples from mass disasters, and small pieces of evidence containing little biological material. Additionally, the maternal inheritance of mtDNA allows scientists to compare a mtDNA profile to reference samples from that person’s mother, brother(s), sister(s), or any other maternally related individuals. All of these individuals have the same mtDNA profiles because all maternal relatives inherit their mtDNA from their mother. Because multiple individuals can have the same mtDNA type, unique identifications are not possible using mtDNA analysis. However, mtDNA performed by the DNA Analysis Unit II is an excellent technique to use for obtaining information when nDNA analysis is not feasible. Additionally, the mtDNA-typing results related to missing-person cases may be uploaded into the CODIS database.

Questions concerning nuclear DNA testing should be directed to 703-632-8446. Questions concerning mitochondrial DNA testing should be directed to 703-632-7572.
Follow the evidence submission directions, including
Requesting Evidence Examinations
and
Packaging and Shipping Evidence.

Case Acceptance Policy of the DNA Analysis Unit I

  • The DNAUI accepts FBI cases for serological and nDNA analysis. FBI cases are prioritized according to the FBI’s priorities of counterterrorism; cyber-based/high-technology crimes; public corruption; civil rights; transnational/national criminal organizations/ enterprises; major white-collar crime; significant violent crime; and support of local, state, federal, and international agencies. This includes examinations that characterize biological stains and may identify the source of a stain on an evidentiary item.
  • The DNAUI accepts cases from FBI field offices and legal attachés (LEGATs); other federal agencies (e.g., Bureau of Indian Affairs, DEA); U.S. attorneys’ offices; military tribunals; and duly constituted state, county, and municipal law enforcement agencies in the United States and its territories. The DNAUI also accepts cases that are submitted to the Laboratory from international law enforcement agencies through the FBI LEGATs.
  • Cases are accepted provided that:
    1. The submitting agency is not served by another government forensic DNA laboratory.
    2. The submitted case has not been examined previously by another laboratory.

Case Consideration Policy

  • The DNAUI supports the National Missing Person DNA Database (NMPDD) Program. Cases must be submitted through an NMPDD Program Manager for entry into the Biological Relatives of Missing Persons or Unidentified Human Remains Indexes. The NMPDD provides investigators with an opportunity to identify missing and unidentified persons on a national level.
  • The DNAUI maintains the Federal Convicted Offender (FCO) Program, which supports the collection and nDNA analysis of samples collected from more than 500 sites across the United States.
  • The DNAUI requires known reference sample(s) for comparison with evidence materials. DNA profiles located in the National DNA Index System (NDIS) Convicted Offender database cannot be used as references.
  • The DNAUI does not conduct low-copynumber (LCN) or “touch DNA” examinations (i.e., DNA from fingerprints, pieces of paper, handled objects, etc.). Items such as steering wheels and firearms may be appropriate for analysis.
  • The DNAUI does not perform kinship analysis. Questions concerning kinship, paternity/ maternity comparisons, etc., should be directed to the DNAUI at
    703-632-8446
    .

As necessary:

  • DNAUI cases may be prioritized according to scheduled trial dates or other case-specific information.
  • The DNAUI does not examine evidence from property crime cases unless violence that results in bodily harm is used in the commission of the crime.
  • For cases in which the FBI Laboratory has conducted previous DNA or serological testing, a review of the case file will be conducted to determine if additional examinations will be conducted.

Case Acceptance Policy of the DNA Analysis Unit II

All FBI cases that meet the suitability guidelines (outlined below) will be considered for mtDNA analysis in the DNAUII. Cases involving terrorism are given highest priority, followed by counterintelligence matters and violent crimes. Questions regarding case and evidence suitability should be directed to the DNAUII at
703-632-7572
.

State and local law enforcement agencies needing mtDNA analysis must contact the DNAUII for more information regarding evidence submission. Agencies may call
703-632-7572
to discuss the needs of the investigation and the evidence, following the suitability guidelines outlined below. Analysis of the evidence will be performed by one of the unit’s regional mtDNA laboratories and is cost-free to state and local law enforcement agencies in the United States and its territories. Travel expenses for examiners testifying in state and local cases are also paid by the FBI Laboratory. FBI entities may refer to the FBI Laboratory/DNAUII web page on the FBI intranet for additional information on the regional mtDNA laboratories.

Missing-person cases involving unidentified human remains and relatives of missing persons are managed and entered into the NDIS in the DNAUII by members of the NMPDD Program. Evidence from these investigations also undergoes mtDNA analysis in the DNAUII or in one of the regional mtDNA laboratories. Contact the NMPDD Program Manager at
703-632-7582
for questions regarding missing-person evidence submission. FBI entities may refer to the FBI Laboratory/DNAUII web page on the FBI intranet for additional information on the NMPDD Program.

Suitability of Mitochondrial DNA Analysis

Mitochondrial DNA analysis has been applied successfully to evidence from violent crimes, typically homicide, sexual assault, and assault. It is important to remember, however, that mtDNA analysis is appropriate in only a small portion of cases where mtDNA evidence is present.

Experience shows that about 75 percent of cases in which mtDNA analysis is actually performed involve hair evidence where only the hair shaft is present. Most often, mtDNA analysis is justified for hair evidence when no tissue is present on the hair root. Mitochondrial DNA analysis in missing-person cases is appropriate only when bone or teeth specimens can be verified as of human origin.

To avoid the misapplication of mtDNA analysis resources, cases must be reviewed carefully for their scenarios, the possibility of other tests on available evidence (e.g., nDNA), and the selection of specimens having the greatest probative value.

Regardless of the type of biological evidence, mtDNA analysis
generally will not be performed
when nDNA results exist on items of similar origin. For example, if nDNA results are obtained from semen identified on a victim’s vaginal swabs and there is no allegation of multiple assailants, mtDNA analysis would not be performed on an associated pubic hair found in the pubic-hair combings of the victim.

Current forensic mtDNA techniques cannot effectively distinguish between sources or relative quantities of DNA. Consequently, mtDNA is not appropriate for evidence containing possible mixed sources of DNA
such as semen stains from sexual assaults
.

Mitochondrial DNA analysis
generally will not be performed on bloodstains
unless the victim’s reference samples are not available or other appropriate reference samples are unavailable for nDNA analysis. For example, a kidnapping victim is missing, but a bloodstain is found in the suspect’s vehicle and only a maternal relative’s (e.g., mother, sibling) reference sample is available for the victim. In that case, mtDNA analysis could be conducted using a portion of the vehicle bloodstain, the maternal relative’s reference sample, and the suspect’s known sample.

Mitochondrial DNA Analysis of Hair Evidence

Mitochondrial DNA analysis should be performed on probative hair samples
only if they are deemed
unsuitable
for nDNA analysis
. Only those hairs having greatest probative value should be subjected to mtDNA analysis. If several similar probative hair specimens are submitted from one source of evidence, mtDNA analysis should be performed on only 1-2 hairs. For example, if 10 hairs collected from a victim’s body are microscopically associated with the suspect, no more than 2 hairs will be analyzed.

Submission guidelines for mtDNA cases must include the following points for hair evidence:

  • Known victim hair samples (of all types) must be submitted to determine whether evidence hairs are similar or dissimilar to the victim’s hair.
  • If evidence includes specimens dissimilar to the victim, known suspect hair samples (of all types) should be obtained.

Mitochondrial DNA analysis generally will be performed on all probative microscopic hair associations.
In addition, the following types of hairs are considered for mtDNA analysis, if probative:

  • Hairs that exhibit “microscopic similarities and slight differences” (e.g., because of prolonged time between the crime and collection of reference samples, environmental or artificial changes to hair, or the suitability of reference samples or questioned hair).
  • Hairs that are not suitable for microscopic comparison purposes (e.g., body-area hairs, hair fragments, or any other factor that eliminates the possibility of performing a comparison). In such cases, however, the hair must be probative (e.g., apparent foreign hair in the pubic-hair combing of the victim).
  • Hairs that are suitable for microscopic comparison purposes but, for valid reasons, are not suitable to compare with the pertinent reference sample (e.g., hair deposited 10 years prior to the collection of the reference hair sample, reference sample is from an individual whose hair is artificially treated after the crime date). Regardless, the hair must be probative.

Unidentified Human Remains

Prior to mtDNA analysis, bone or teeth specimens should be examined by a forensic anthropologist or odontologist or a similarly qualified individual. Submissions of such items should be accompanied by a written report that verifies human origin by a qualified expert.

Documenting, Collecting, Packaging, and Preserving DNA Evidence

If DNA evidence is not properly documented, collected, packaged, and preserved, it will not meet the legal and scientific requirements for admissibility in a court of law.

  • If DNA evidence is not properly documented, its origin can be questioned.
  • If it is not properly collected, biological activity can be lost.
  • If it is not properly packaged, contamination can occur.
  • If it is not properly preserved, decomposition and deterioration can occur.

When DNA evidence is transferred by direct or secondary (indirect) means, it remains on surfaces by absorption or adherence. In general, liquid biological evidence is absorbed into surfaces, and solid biological evidence adheres to surfaces. Collecting, packaging, and preserving DNA evidence depends on the liquid or solid state and the condition of the evidence.

The more evidence retains its original integrity until it reaches the Laboratory, the greater the possibility of conducting useful examinations. It may be necessary to use a variety of techniques to collect suspected body-fluid evidence.

Collecting Known Samples

Blood

  • Only qualified medical personnel should collect blood samples from a person.
  • Collect at least two 5-mL tubes of blood in purple-top tubes, which contain EDTA as a preservative, for DNA analysis. Collect drug or alcohol-testing samples in gray-top tubes, which contain NaF (sodium fluoride).
  • Label each tube with the date, time, person’s name, location, collector’s name, case number, and evidence number.
  • Refrigerate, do not freeze, liquid blood samples (tubes may break if frozen). Use cold packs, not dry ice, during shipping.
  • Pack liquid blood tubes individually in Styrofoam or cylindrical tubes with absorbent material surrounding the tubes.
  • Package blood samples from different individuals separately.
  • Label the outer container “KEEP IN A COOL, DRY PLACE,” “REFRIGERATE ON ARRIVAL,” and “BIOHAZARD.”
  • Submit to the Laboratory as soon as possible.

Buccal (Oral) Swabs

  • Use clean cotton swabs to collect buccal (oral) samples. Rub the inside surfaces of the cheeks thoroughly.
  • Air-dry the swabs and place in clean paper or an envelope with sealed corners. Do not use plastic containers.
  • Identify each sample with the date, time, person’s name, location, collector’s name, case number, and evidence number.
  • Package oral samples from different individuals separately.
  • Buccal samples do not need to be refrigerated.
  • Submit to the Laboratory as soon as possible.
  • If a reference blood or oral sample cannot be obtained, an alternate reference sample may be submitted (for nuclear examinations only). This may include such items as surgical samples, Pap smear slides, pulled teeth, or a toothbrush or item of clothing known to be used solely by the individual of interest.

Blood on a Person

  • Absorb suspected liquid blood onto a clean cotton cloth or swab. Air-dry the cloth or swab and pack in clean paper or an envelope with sealed corners. Do not use plastic containers.
  • Absorb suspected dried blood onto a clean cotton cloth or swab moistened with distilled water. Air-dry the cloth or swab and pack in clean paper or an envelope with sealed corners. Do not use plastic containers.

Blood on Surfaces or in Snow or Water

  • Absorb suspected liquid blood or blood clots onto a clean cotton cloth or swab. Air-dry the cloth or swab and pack in clean paper or an envelope with sealed corners. Do not use plastic containers.
  • Collect suspected blood in snow or water immediately to avoid further dilution. Eliminate as much snow as possible. Place in a clean, airtight container. Freeze the evidence and submit to the Laboratory as soon as possible.

Bloodstains

  • Air-dry suspected wet bloodstained garments. Wrap dried bloodstained garments in clean paper. Do not place wet or dried garments in plastic or airtight containers. Place all debris or residue from the garments in clean paper or an envelope with sealed corners.
  • Air-dry small suspected wet bloodstained objects and submit the objects to the Laboratory. Preserve bloodstain patterns. Avoid creating additional stain patterns during drying and packaging. Pack to prevent stain removal by abrasive action during shipping. Pack in clean paper. Do not use plastic containers.
  • When possible, cut a large sample of suspected bloodstains from immovable objects with a clean, sharp instrument. Pack to prevent stain removal by abrasive action during shipping. Pack in clean paper. Do not use plastic containers.
  • Absorb suspected dried bloodstains on immovable objects onto a clean cotton cloth or swab moistened with distilled water. Air-dry the cloth or swab and pack in clean paper or an envelope with sealed corners. Do not use plastic containers.

Blood Examination Request Letter

A blood examination request letter must contain the following information:

  • A brief statement of facts relating to the case.
  • Claims made by the suspect(s) regarding the source of the blood.
  • Whether animal blood is present.
  • Whether the stains were laundered or diluted with other body fluids.
  • Information regarding the health of the victim(s) and suspect(s), including the presence of such infections as AIDS, hepatitis, and tuberculosis.

Semen and Semen Stains

  • Absorb suspected liquid semen onto a clean cotton cloth or swab. Air-dry the cloth or swab and pack in clean paper or an envelope with sealed corners. Do not use plastic containers.
  • Submit small suspected dry semen-stained objects to the Laboratory. Pack to prevent stain removal by abrasive action during shipping. Pack in clean paper. Do not use plastic containers.
  • When possible, cut a large sample of suspected semen stains from immovable objects with a clean, sharp instrument. Pack to prevent stain removal by abrasive action during shipping. Pack in clean paper. Do not use plastic containers.
  • Absorb suspected dried semen stains on immovable objects onto a clean cotton cloth or swab moistened with distilled water. Air-dry the swab or cloth and place in clean paper or an envelope with sealed corners. Do not use plastic containers.
  • Note: It is not necessary to collect reference seminal fluid for comparison. Refer to the
    Collecting Known Samples
    section for more information.

Seminal Evidence from Sexual Assault Victims

  • Sexual assault victims must be medically examined in a hospital or a physician’s office using a standard sexual assault evidence kit to collect vaginal, oral, and anal evidence.
  • Refrigerate and submit the evidence to the Laboratory as soon as possible.

Saliva and Urine, Other Sources of Body-Fluid Evidence

  • Absorb suspected liquid saliva or urine onto a clean cotton cloth or swab. Air-dry the cloth or swab and pack in clean paper or an envelope with sealed corners. Do not use plastic containers.
  • Submit small suspected dry saliva- or urinestained objects to the Laboratory. Pack to prevent stain removal by abrasive action during shipping. Pack in clean paper or an envelope with sealed corners. Do not use plastic containers.
  • When possible, cut a large sample of suspected saliva or urine stains from immovable objects with a clean, sharp instrument. Pack to prevent stain removal by abrasive action during shipping. Pack in clean paper. Do not use plastic containers.
  • Pick up cigarette butts with gloved hands or clean forceps. Do not submit ashes. Air-dry and place the cigarette butts from the same location (e.g., ashtray) in clean paper or an envelope with sealed corners. Do not submit the ashtray unless a latent print examination is requested. Package the ashtray separately. Do not use plastic containers.
  • Pick up chewing gum with gloved hands or clean forceps. Air-dry and place in clean paper or an envelope with sealed corners. Do not use plastic containers.
  • Pick up envelopes and stamps with gloved hands or clean forceps and place in a clean envelope. Do not use plastic containers.

Hair

  • Pick up hair carefully with clean forceps to prevent damaging the root tissue.
  • Air-dry hair mixed with suspected body fluids.
  • Package each group of hair separately in clean paper or an envelope with sealed corners. Do not use plastic containers.
  • Refrigerate and submit to the Laboratory as soon as possible.

Tissue, Bones, and Teeth

Call the Laboratory at
703-632-7572
prior to submitting suspected tissue, bones, or teeth to ensure that the evidence will be accepted for examination. The communication accompanying the evidence must reference the telephone conversation accepting the evidence.

  • Pick up suspected tissue, bones, and teeth with gloved hands or clean forceps.
  • Collect 1-2 cubic inches of red skeletal muscle.
  • Submit whole bones. Cutting bones increases the possibility of contamination.
  • Collect teeth in the following order:
    1. Nonrestored molar.
    2. Nonrestored premolar.
    3. Nonrestored canine.
    4. Nonrestored front tooth.
    5. Restored molar.
    6. Restored premolar.
    7. Restored canine.
    8. Restored front tooth.
  • Place tissue samples in a clean, airtight plastic container without formalin or formaldehyde. Place teeth and bone samples in clean paper or an envelope with sealed corners.
  • Freeze the evidence, place in Styrofoam containers, and ship overnight on dry ice.

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