Forensics 101

This past Saturday I attended my chapter workshop where we had a forensics crime lab guy come in to chat with us. Although I don’t write Romantic Suspense, I enjoy a good crime scene, the same as everybody else. I learned some interesting things! I thought I’d share them below, for anyone who’s interested.

1. Crime evidence is never stored in plastic bags like you see on television. It’s stored in cardboard boxes designed specifically for cotton swabs, in paper bags, or other paper containers. Plastic would cause some evidence (e.g. blood) to smell horrible.

2. DNA evidence can be found on soda bottles with saliva, using blood, and skin cells off a gun trigger.

3. If you have an unidentified stain and you want to determine if it’s blood, there are chemical tests you can do. Sometimes on the tv shows, they’ll treat the stain directly for drama. In real life, a cotton swab is used to obtain a sample. Then there are several tests. You often see them using Luminol on tv, the glow-in-the-dark chemical that makes blood obvious. There’s a problem with Luminol, however. It reacts with bleach. So if the criminal tries to clean up with bleach, the Luminol will be so bright, it’s useless. Most cops use the Leuco-malachite test (LMG). It’s a two-part test where you use a green reagent (hydrogen peroxide) and leucomalachite. When you add the two substances to the suspected blood, it turns blue. The problem is, there can be false positives. If the suspect was slicing up roast beef, for example, blood traces would be evident.

4. Police will never touch evidence. If they do, they have to submit it themselves and fill out a ton of paperwork. Not worth it.

5. Corpses are not outlined in chalk at the scene. They just leave them there until they’re done with the scene.

6. Wounded men/women might be outlined, since they won’t leave them to bleed to death while they’re collecting evidence.

7. Digital photography isn’t used very often when photographing crime scenes. Most juries understand that digital photographs can be altered and there isn’t much trust there.

8. Bullets and cartridge cases can be matched to the gun from which they were fired by the rifling ridges marked on the bullet from the gun chamber and also from the firing pin.

9. Revolvers don’t expel cartridges. They remain in the chamber, which means criminals don’t have to pick up cartridges.

10. The most common guns on the streets are a .9 mm and a .380 automatic.

In other news, I worked out my plotting problems and wrote 5 pages yesterday. All in all, a good day.