Read FBI Handbook of Crime Scene Forensics Online

Authors: Federal Bureau of Investigation

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

FBI Handbook of Crime Scene Forensics (6 page)

BOOK: FBI Handbook of Crime Scene Forensics
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Pharmaceutical Examinations

Pharmaceutical examinations can identify constituents, active ingredients, quantity, and weight.

  • Questions concerning pharmaceutical evidence should be directed to 703-632-8441.
    Follow the evidence submission directions, including
    Requesting Evidence Examinations
    and
    Packaging and Shipping Evidence
    .
  • List the names of the pharmaceuticals and information on their use.
  • If possible, submit pharmaceuticals in original containers.
Polymer Examinations

Polymer evidence typically consists of pieces of plastic or other manufactured materials. The source, use, or manufacturer of polymer evidence usually cannot be identified by compositional analysis.

Motor vehicle trim can be compared with plastic remaining on property struck in a hit-and-run case. The manufacturer, make, model, and model year of a vehicle can be determined if a manufacturer’s part number is on the trim.

Plastics in wire insulation and miscellaneous plastics such as buttons can be compared with known sources.

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

  • When a motor vehicle has been in an accident, fragments (e.g., plastic lens covers) can be left at the scene. These pieces can be physically reconstructed with the remnants of the fixture left on the car. Collect and package the fragments carefully to keep the edges intact.
  • Search the accident or crime scene and personal effects of the victim(s) to locate plastic fragments. Submit fragments in leakproof containers such as film canisters or plastic pill bottles. Do not use cotton or paper containers.
  • Remove damaged suspect motor vehicle parts, and package separately in resealable plastic bags or boxes.
  • If possible, submit entire items (e.g., clothing) with potential or smeared polymeric transfers. Package separately in paper bags. If the entire item cannot be submitted, cut with a clean, sharp instrument a section where the transfer is suspected. Collect an unstained control sample. Pack to prevent stain removal by abrasive action during shipping. Pack in clean paper. Do not use plastic containers.
Product-Tampering Examinations

Product tampering is when a commercial product is intentionally distorted to harm someone or to extort money or other thing of value. Examples range from drug tampering in medical environments, food adulteration in supermarkets, and the combination of tampering and altering in domestic settings.

The Laboratory will not assess manufacturing quality control or product specifications in commercial products.

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

  • Submit control samples of the unadulterated product.
  • Package and ship control and suspect samples separately to avoid contamination. Submit samples in leakproof containers such as film canisters or plastic pill bottles. Do not use paper or glass containers.
  • Use caution to prevent the destruction of latent prints.
Questioned Document Examinations
Handwriting and Hand Printing

The examination and comparison of handwriting characteristics can determine the origin or authenticity of questioned writing, although not all handwriting is identifiable with a specific writer. Intent and such traits as age, sex, and personality cannot be determined from handwriting examinations. Some reasons for inconclusive results include:

  • Limited questioned and/or known writing.
  • Lack of sufficiently comparable known writing for comparison.
  • Lack of contemporaneous writing or lapse of time between execution of questioned and known writing.
  • Distortion or disguise in the questioned and/or known writing.
  • Lack of sufficient identifying characteristics.
  • Submission of photocopied evidence instead of original evidence.
Procedures for Obtaining Known Writing Exemplars
  • The text, size of paper, space available for writing, writing instrument, and writing style (handwriting or hand printing) must be as close to the original writing as possible.
  • Give verbal or typewritten instructions concerning the text to be written. Do not give instructions on spelling, punctuation, or arrangement of writing.
  • All exemplars must be on separate pieces of paper.
  • The writer and witness must initial and date each page of writing.
  • Do not allow the writer to see the previous exemplars or the questioned writing. Remove each exemplar from the writer’s sight as soon as it is completed.
  • Numerous repetitions may be necessary to obtain naturally prepared writing.
  • Obtain exemplars from the right and left hands.
  • Obtain hand-printing exemplars in upper- and lowercase letters.
  • Obtain a sufficient quantity of exemplars to account for natural variation in the writing.
  • Obtain undictated writing such as business records, personal correspondence, and cancelled checks or other documents prepared during the normal course of business activity.
Common Types of Nongenuine Signatures
  • Traced signatures are prepared by directly using a genuine signature as a template or pattern.
  • Simulated signatures are prepared by copying or drawing a genuine signature.
  • Freehand signatures are written in the forger’s normal handwriting with no attempt to copy another’s writing style. Therefore it may be possible to identify the writer(s) who prepared the signature(s).
Altered or Obliterated Writing

Documents can be examined for the presence of altered or obliterated writing, and the original writing may be deciphered.

Typewriting

Questioned typewriting may be identified with the typewriter that produced it. This is most common when the typewriter is a typebar machine. The identification is based on individual characteristics that develop during the manufacturing process and through use and abuse of the typewriter.

Typewriters with interchangeable elements (e.g., ball, printwheel, or thimble) are less likely to be associated with questioned typewriting. However, these typing elements may be positively identified with specific texts by examining individual characteristics of the elements.

Comparison of questioned typewriting with reference standards can determine a possible make and model of the typewriter and/or the typewriter elements.

Carbon-film typewriter ribbons and correction ribbons retain readable text. These ribbons can be compared with questioned typewritten impressions. Generally, fabric ribbons cannot be read or identified.

Procedures for Obtaining Known Typewriting Exemplars
  • If the typewriter has a carbon-film ribbon or correction ribbon, remove it from the typewriter and submit the ribbon to the Laboratory. Insert a new ribbon in the typewriter prior to obtaining exemplars.
  • If the typewriter has a fabric ribbon, remove it from the typewriter and put the typewriter in the stencil position. Place a sheet of carbon paper over a sheet of blank paper and insert both into the typewriter. Allow the typeface to strike the carbon paper. Submit the fabric ribbon and the exemplars typed on the carbon paper to the Laboratory.
  • Obtain two full word-for-word typed exemplars of the questioned text and two typed exemplars of the entire keyboard (all symbols, numbers, and upper- and lowercase letters).
  • Record the make, model, and serial number of the typewriter on the exemplars. Also record the date the exemplars were obtained and the name of the person who typed the exemplars.
  • Obtain the typewriter service and repair history, if available.
  • Normally it is not necessary to send the typewriter to the Laboratory; however, in some cases, the examiner will request the typewriter. It must be packed securely to prevent damage during shipment. Typewriter elements (e.g., ball, printwheel, or thimble) also must be submitted to the Laboratory.
Photocopies or Facsimiles

Photocopies or facsimiles of documents can be identified with the machine used to produce them if the exemplars and questioned documents are relatively contemporaneous. The possible make and model of the photocopier or facsimile machine sometimes can be determined.

Procedures for Obtaining Known Photocopy Exemplars
  • Obtain at least 10 exemplars without a document on the glass plate and with the cover down.
  • Obtain at least 10 exemplars without a document on the glass plate and with the cover up.
  • Obtain at least 10 exemplars with a document on the glass plate and the cover down.
  • Obtain at least 10 exemplars with a document through the automatic document feeder, if applicable.
  • Record on each exemplar the date the exemplars were obtained, the name of the person who prepared the exemplars, and the conditions under which the exemplars were made.
  • Record the make, model, and serial number of the photocopier; information about the toner supplies and components; whether the paper supply is sheet- or roll-fed; and options such as color, reduction, enlargement, zoom, mask, trim, and editor board.
  • Do not store or ship photocopies in plastic envelopes.
Graphic Arts (Commercial and Office Printing)

Printed documents can be associated with a common source or identified with known commercial printing paraphernalia such as artwork, negatives, and plates or office printing devices such as ink-jet or laser printers.

Paper

Torn edges can be compared. The paper manufacturer can be determined if a watermark is present. Paper can be examined for indented writing. Do not rub the indentations with a pencil. Do not add indentations by writing on top of the evidence.

Burned or Charred Paper

Burned or charred documents (not completely reduced to ash) may be deciphered and stabilized. The document must be handled minimally. The document must be shipped in the container in which it was burned, in polyester film encapsulation, or between layers of cotton in a rigid container.

Age of a Document

The earliest date a document could have been prepared may be determined by examining various physical characteristics, including watermarks, indented writing, printing, typewriting, and inks
.

Carbon Paper or Carbon-Film Ribbon

Used carbon paper or a carbon-film ribbon can be examined to disclose the content of the text.

Checkwriters

A checkwriter impression can be compared with a known source. Examining checkwriter impressions may determine the brand or model of the checkwriter.

Embossings and Seals

An embossed or seal impression can be compared with a known source. Submit the device to the Laboratory.

Rubber Stamps

A rubber-stamp impression can be compared with a known source. Submit the rubber stamp to the Laboratory uncleaned.

Plastic Bags

Plastic bags (e.g., sandwich and garbage bags) can be compared with a roll or box of bags.

Anonymous Letter File

The Anonymous Letter File contains images of anonymous and/or threatening communications submitted to the Questioned Documents Unit for examination. This file can be searched in an attempt to associate text from a communication in one case with text from communications in other cases.

Bank Robbery Note File

The Bank Robbery Note File contains images of notes used in bank robberies. This file can be searched in an attempt to associate text from one bank robbery note with text from bank robbery notes in other cases.

Questions concerning documentary evidence should be directed to 703-632-8444.
Follow the evidence submission directions, including
Requesting Evidence Examinations
and
Packaging and Shipping Evidence
.

  • Documentary evidence must be preserved in the condition in which it was found. It must not be unnecessarily folded, torn, marked, soiled, stamped, or written on or handled excessively. Protect the evidence from inadvertent indented writing. Mark documents unobtrusively by writing the collector’s initials, date, and other information in pencil.
  • Whenever possible, submit the original evidence to the Laboratory. The lack of detail in photocopies makes examinations difficult and often will result in inconclusive opinions. Copies are sufficient for reference-file searches.
  • Do not store or ship photocopies in plastic envelopes.
Rope and Cordage Examinations

A piece of rope or cord can be compared with a questioned rope or cord. The composition, construction, color, and diameter can be determined. If a tracer is present, the manufacturer can be determined.

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

  • Submit the entire rope or cord. If the rope or cord must be cut, specify which end was cut during evidence collection.
  • Label the known and questioned samples.
  • Handle the sections of rope or cord carefully to prevent loss of trace material or contamination.
  • Submit in heat-sealed or resealable plastic or paper bags.
BOOK: FBI Handbook of Crime Scene Forensics
11.85Mb size Format: txt, pdf, ePub
ads

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