Friday, September 11, 2009


© Lisa Black 2009 all rights reserved

Writing mysteries assures us that our characters will wind up at a crime scene at least once during the course of the book. I’m also a forensic specialist, so I can wind up at a crime scene once a day.

The ‘scene’ itself can be very loosely or very rigidly defined. Yellow crime scene tape doesn’t just look cool—it serves a purpose. It delineates the area in police custody. The first thing you do once you put the tape up is remove everyone who doesn’t belong inside it, such as witnesses, suspects, neighbors, etc. There should be one point of entry and exit so that the officer with the ‘contamination list’ (such a negative term!) can keep track of who was there and who wasn’t, and when. Anyone entering the scene is subject to subpoena and therefore may be called to testify in court as to what they did there. This is usually enough to keep out any police officers (especially higher-ups) who show up only to see and be seen. This isn’t just mindless bookkeeping—any evidence found inside the tape is in pretty good shape, but any evidence found outside the tape could be challenged in court as it was not in police custody and subject to possible contamination. (Attorneys seem to think ‘contamination’ is a magic word that can mean whatever they want it to mean.) Never mind that the entire scene was not in police custody for the five hours before the body was discovered, but hey, we do what we can.

Crime scene tape might be put up for a suspicious death or any other serious circumstance, then taken down and disregarded when it has been decided that the death was natural or whatever. And then you get those gung ho types who put it up for anything from a smash-n-grab to a fender bender. It’s $20 a roll, guys, and the budget’s been slashed.

Collecting evidence…yes, we put numbered or lettered markers by small items to photograph them. Photograph everything before you move it! Do not pick up a metal item, such as a spent casing, with metal tweezers (unless the ends are coated with rubber). You don’t want to leave more tool marks on an item that’s going to be examined for tool marks. And forget those handy little self-sealing plastic bags. We put nothing in plastic, ever. Plastic bags have static electricity and stick to the surface of things, making it less like to recover a fingerprint, and also retain any moisture, which might make items mold, rot or rust. The only thing we can sorta, kind tolerate in plastic are paper items like letters or envelopes. I’ve only used plastic jars for insects (one jar with alcohol to arrest the insects at their current stage of development, and one jar with a damp paper towel to keep them alive—for a while—so that they can be grown to maturity and identified).

Of course you know no one in law enforcement calls the killer/burglar/unknown subject a ‘perp.’ Usually they’re just ‘the guy.’ If there’s time for more flowery language, he might be ‘the scumbag.’ We often wind up speaking entirely in pronouns—after all, the relationship between the involved parties is more relevant than their given names. A conversation might go like this: “So the lady that lives here, her husband says she’s wacko and always going off in a huff, but mom says that he pushed her against the wall last week and he’s always yelling at her and was supposed to take her dog to the vet today and she wouldn’t miss that, and the kid says mom said she was going to buy a gun the day before yesterday—” And yes, it can get confusing, so that someone like me interrupts to clarify: “Which mom was going to buy a gun? The kid’s mom (the victim) or the kid’s grandmother (the victim’s mom)? Who did the husband push around last week--and whose dog had a vet appointment--the missing mom or the missing mom’s mom?”

Speaking of guns, the presence or absence of gunshot residue does not prove someone did or did not fire a gun.

We don’t all have handy databases of lipstick, perfume, crayons, fabric softener or honey. Manufacturers make their living with these formulas; they’re hardly likely to make that information public. Also, you cannot scan in a fingerprint and search everyone who has ever been fingerprinted in the entire US, including job applicants and military. Usually you will be searching only local arrestees, maybe the whole state. You might have lowered lighting in Dispatch and in the latent prints unit so that staff can better see the computer screens (though I work in latent prints and prefer normal lighting); every other area of the lab would have the brightest lights possible. We do not tell the detectives what to do—they are in charge of the investigation, not us. It is in the best interest of both parties to cooperate and advise each other, but ultimately it is the detective who decides who to arrest, who to question, and where to search.

If you have the time, you might want to attend a citizen’s academy program at your local police department. This will give you a great overview of how crimes are actually investigated and, better yet, you might meet personnel you can later use as a resource when you have a question.

Oh, and we don’t wear low-cut designer sweaters or high heels. When you work around blood, bleach, staining reagents and just plain dirt, you don’t wear anything that you’d be really upset about ruining. We’re not all young, sexy, single and angst-ridden. On the plus side, we’re generally funnier and a lot easier to get along with.

Just go easy on the crime scene tape.

About the author:

Lisa Black is a forensic specialist with a police department in Florida. Before that she worked as a forensic scientist with the coroner's office in Cleveland, Ohio. Evidence of Murder is her fourth published thriller.


Kim Smith said...

Fascinating stuff! I am curious to know if you don't use plastic bags, then what do you use to collect stuff?

s.w. vaughn said...

This is great - and hilarious! I've seen a lot of these misconceptions about police work and forensics in fiction. Thanks for giving us the real deal!

Sheila Deeth said...

Wow. This was great, and fun. Thanks.

Marta Stephens said...

Lisa, thanks so much for sharing your crime wisdom with us! As a crime writer myself I've research every detail of crime scene investigation and it's always encouraging to me when I read a post written by one in the profession and know that I got it right!

Aaron Paul Lazar said...

Lisa, what a great piece! Thanks for guest blogging with us today. I've never met a real forensic specialist and am sad to say all of my experiences in that regard have been through Hollywood! Your advice is wonderful and much appreciated!

Susan Breen said...

Very helpful. Thank you.

Lisa Black said...

Instead of plastic bags, we use paper. Paper bags, paper envelopes, and cardboard boxes.

There's nothing like trying to stuff a full size down comforter into a paper bag. It's a pain and a half!