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Proper evidence collection is a must if your protagonists have any shred of hope of winning a murder case in the fictional courtrooms you’ve fabricated solely from ink and paper.

In fact, the only chance your DNA DA has is to present fact when testifying to the make-believe judges and juries you’ve concocted in those fantasy worlds that live in the far corners of your twisted minds.

So here are a scant few basics to correct the errors I’ve found lately while reading during my personal graveyard shift, otherwise known as the hours between midnight and three when insomnia pulls my eyelids wide open.

Anyway, here’s how to properly collect and store the follow items of evidence (please do not use television as a source for this stuff!):

Cigarette butts – Do not use bare hands to collect. Instead, used gloved hands or forceps. Do not submit ashes. Always air dry the butts before packaging and, to preserve DNA, do NOT package in plastic bags or other plastic containers.

Chewing gum – Collect using forceps or gloved hands. As with cigarette butts, air dry and  then place into a clean paper envelope or similar packaging. Never use plastic bags or other plastic containers. Plastic acts as an incubator for bacteria, which could degrade or destroy DNA.

Hair – Use caution to prevent damaging the the root ball. Collect gently, using clean forceps (clean, to prevent cross-contamination of DNA). If the hair is wet or damp, air dry before packaging in paper with edges folded and sealed, or place and seal in a paper envelope.

Human or animal tissue – Collect approximately two cubic inches of red muscular tissue (if possible). As with other DNA evidence collection of solid material, use clean forceps or gloves. Remember to change gloves when handling different items to avoid cross-contamination. Place the tissue in a clean, airtight container. Never use formalin or other preservatives such as formaldahyde. When shipping to a testing lab, freeze the sample and send via overnight transportation service, packed in dry ice in a styrofoam container, or hand deliver.

Bones and teeth – Use forceps and/or gloved hands for collection. Collect whole bones if possible. Place bones and teeth in paper containers with sealed edges. Store out of light and humidity, and may be frozen if samples are previously air dried.

 

 

 

Blood and saliva –  Store out of light and humidity, and may be frozen if samples are previously air dried.

 

There’s more to evidence collection than merely bagging and tagging bloody clothing and spent bullet casings. Crime scene techs are highly trained, skilled members of police agencies and forensic laboratories who more often than not provide the keys to solving cases.

In the “good old days,” many officers, including patrol officers (some still do, especially in smaller departments), collected their own evidence. They plodded into and poked around crime scenes, determining what items they thought might be of some value, and then tossed those things into some sort of containers—grocery bags, envelopes, boxes, and even the cellophane wrappings from cigarette packs. In those days there wasn’t a lot of consideration for sterility, and DNA hadn’t yet made it’s way on the scene.

When investigators finally discovered plastic sandwich and ziplock bags you’d have thought they’d won the lottery, because packaging evidence had suddenly become a breeze. The problem with those new-fangled containers, though, was that detectives were placing everything in them, not knowing they could be destroying or damaging evidence instead of preserving it. And that brings us to the question of Paper or Plastic?

There’s a simple rule of thumb for deciding which type of evidence packaging—wet evidence goes in paper containers (wet evidence can degrade if placed inside plastic containers) and dry evidence goes in plastic. Items that could be cross-contaminated must be packaged separately. There’s a rule of thumb for other types of evidence, too, and here’s a handy list for the proper packaging of those items.

Hair – Double packaging in paper is best. However, if the hair is completely dry, plastic will work in a pinch. Hairs recovered from different locations must be packaged separately and labeled accordingly. Tape all packaging seams.

Fibers – Dry, and tape-lifted, fibers may be placed inside plastic containers.

Rope, twine, and other cordage – Paper or plastic.

Paint chips – Place inside folded paper. Then place the paperfold inside an envelope.

Tools – Paper or cardboard.

Tape – Wear non-powdered gloves when handling tape. Submit samples inside plastic. If the tape is stuck to an item the item must be submitted with the tape still attached. Do not remove the tape!

Glass – Wrap in paper. Smaller pieces may be placed inside appropriate size cartons.

Arson and other fire evidence – Airtight metal containers. Unused paint cans work best.

Dried stains – Wrap stained item in paper or place inside cardboard box. Large items – moisten swab with distilled water, swab the stain, and package in paper or cardboard after drying.

Blood – Allow to air dry and then package in paper.

Evidence drying lockers

DNA – NEVER use plastic!
And when I mentioned that wet evidence is packaged in paper containers I did NOT mean to pour liquids into paper bags. Instead, items that contain wet evidence (bloody and/or semen-stained clothing, etc.) should be placed into paper containers.