Forensic science has grown increasingly quantitative and technology intensive, maybe even reaching some of the points implied by TV shows like CSI. Few writers can analyze DNA or microscopically compare bullets or shell casings, but some parts of the research we can do, and those same ones can be done by our cops. For example, with a few household items we can lift fingerprints, just as they are often lifted and compared by detectives.
In one mystery I wrote, I wanted the cop to determine the time of an attack, so I had him look at some blood splatters. I’m sure there are authoritative treatises on the subject, but here it was more fun, and more locally relevant, for him to do his own test. Anyway, what cop wouldn’t rather play with blood than read the treatise “On the Siccicity of Hematogenic Stilliticious Deposits.”
There are not many areas where a writer can easily duplicate what a forensic lab would do, but it is easy to do some blood splatter checking. Now this might not hold up in court, but I, like my detective, pricked my finger and flung some blood on the wall at the time of day in the story and watched what happened. A small town is unlikely to have a blood splatter specialist, and if the information must be analyzed rapidly and little time is available to call in the state bureau of investigation, your cop might have to do it, anyway.
Instead of wading through the scientific papers and interpolating the results for his weather conditions, which my cop was no more interested in doing than I was, he did my experiment. It told him, under identical conditions of temperature, humidity and time of day, just how much a dribble might run, how fast it changed from red to brown, how fast it crusted over, and how fast it became solid.
Luminol to see blood? Don’t have it. Laser to develop finger prints on paper? No way. How fast blood dries on a hot Mississippi day? That I checked. So did my cop.