Crime scene investigators encounter many different type of evidence found at scenes: physical, biological, trace, and digital just to name a few. Collecting evidence is a vital part of what crime scene investigators do and knowing how and what to collect is the corner stone of their duties.

Knowing how to preserve evidence is another key aspect of evidence collection. Agencies have different shapes and sizes of collection materials and in fact, some agencies will spend extra fees to have their agency name on each of the packaging container, envelop, or bag.

Coin envelopes are used for smaller items of evidence such as bullets, cartridge cases, swabs, and glass fragments. There is a wide variety of sizes and shapes for other items as well. Specific envelopes to house and protect lift cards (latent fingerprint cards). Money (bills) have a specific envelope designated solely for that purpose.

Once an item has been placed inside the specific package whether it be an envelope, bag, or container, evidence tape secures the package preventing anyone from tampering with the package. The CSI will always place his/her initial along with the date across the evidence tape showing who and when the evidence was packaged.

Trace Evidence

May consist of debris such as dirt, soil, sand, gravel, grass, leaves, twigs, adhesives and tape, fibers, glass, or bullet fragments.

When trace evidence is identified the following steps in the collection of the evidence is outlined below:

  • Document and photograph the evidence
  • Properly secure the evidence by placing in a paper bag or envelope
  • Close, seal, or tape the paper bag or envelope. The examiner must initial, date, and time across the sealed area
  • Label the bag or envelope with the patient's identifying information
  • Examiner must place signature, date, and time on the envelope[3]

Biological Evidence

May consist of blood, skin, hair, semen, saliva, and urine.

  • Swabs (cotton tip applicators) collected for biological evidence may include buccal, oral, skin, fingernail, bitemarks, perineal, perianal, vaginal, cervical Os, penile, scrotum, rectal
  • Hair collected is placed in an envelope

The same process for packaging, securing, and maintaining the evidence as outlined above is used for the collection of trace evidence

Visit this link to learn more about evidence collection.