Free FBI Handbook of Crime Scene Forensics by Federal Bureau of Investigation Page A

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.
    Safe-Insulation Examinations
    Safe insulation can be compared to a known source. Examinations of safe insulation sometimes can determine the manufacturer.
    Questions concerning safe-insulation evidence should be directed to 703-632-8449. Follow the evidence submission directions, including Requesting Evidence Examinations and Packaging and Shipping Evidence .
Collect safe-insulation samples from damaged areas.
Safe insulation 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.
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.
    Serial-Number Examinations
    Obliterated serial or identification numbers—including markings on metal, wood, plastic, and fiberglass—often are restorable. Comparisons can be made with suspect dies.
    Questions concerning serial-number evidence should be directed to 703-632-8442. Follow the evidence submission directions, including Requesting Evidence Examinations and Packaging and Shipping Evidence .
For large objects, and if possible, remove the section containing the serial number and submit it to the Laboratory.
If it is not possible to remove the section containing the serial number, make a cast to submit to the Laboratory.
Use an acrylic-surface replica cast kit. Call the Laboratory at 703-632-8442 regarding the appropriate cast kit.
Different formulas are used in different temperatures. If possible, move the evidence to a warm