What does every mystery writer need to know about the real world of crime scene investigation? I found out yesterday when I spent four hours listening to Eric Lopkin, writer and former NYC auxillary policeman, speak extensively about such topics as rules of evidence, police procedures, and who does what at the crime scene.
Here are some of the take-away points he made:
Private investigators are never hired to investigate a murder. They track a spouse, find a
missing person, locate something that is lost.
The gun never remains in the hand of someone who commits suicide. The gun will always drop out of the hand when it goes off.
Almost impossible for a person to stab someone without getting cut themself. The hand that holds the knife keeps going when the knife slows from contact with the body.
Every suicide, unless witnessed, is investigated as a possible homicide.
The word “murder” is a reader term. The word “homicide” is a police term.
Crime scene investigators never talk to witnesses. They are not the primary investigators. They process the scene, take evidence to the lab, and turn over results to detectives in charge.
Know structure of police department in the setting your story is in before you write your
story.
Gun permits are hard to get in NYC but easier to get in other parts of the country.
Suspected murderers don’t usually go to trial for 2-3 years so writers need to be careful about the time-lines in their books.
Two motives: greed and revenge. For serial killers, it is always about revenge but the
victims are not the real person they want revenge on.
When there is a gruesome body found, the civilian or rookie usually vomits, the veteran
cop/detective will make jokes at the crime scene. The detective is not usually caught emotionally off guard by a particularly gruesome crime scene.
Know the technology that the police force has in the setting of your story. It isn’t unusual
for some police departments to have minimal technology.
Tomorrow is a Mystery 
Kathy
July 17, 2011 at 9:59 pm
Thanks for sharing this information. I’ve been postponing speaking with a law enforcement officer about his role in rural Texas, and your post gives me a needed nudge in that direction.
cwall34
July 17, 2011 at 10:50 pm
From what I heard yesterday, the police in rural areas may never see a homicide in their career. Their experience in crime scene investigation can therefore be very limited. If they do have a homicide, the police do the investigation and then they may call in the state police for assistance. They may also bring in federal authorities to help. Technology may be very limited. In our town, which isn’t even rural, the police do not have internet access and have to walk over to the library to go on the internet.
I was also told that many police officers never shoot a gun (except on the shooting range) during their career. If they do, they are immediately put on leave and given counseling.
I think this is all such good stuff for our writing. Good luck in talking to a law enforcement officer!
Kathy
July 18, 2011 at 12:55 am
In my setting (based on my hometown) there are no police. The sheriff’s department, fifteen miles away, would be responsible but would probably call in the Texas Rangers, at least for crime scene investigation. Murders aren’t common, but there have been some fairly high-profile cases in the area over the years. The sheriff has Internet access, but that’s about as high-tech as it gets, I imagine, and most rural areas still depend on dial-up. Of course, I may get info that surprises me–which is why I have to interview someone in the first place.
Alyx Morgan
July 19, 2011 at 4:56 pm
Thank you so much for sharing this, Chris! This is very useful stuff.
cwall34
July 19, 2011 at 11:11 pm
I am glad you found this post helpful! Yesterday we had a murder in our town of about 45,000 people. We are not a rural location but the local police called in the State Police Major Crime Squad for help in the investigation. In my current work in progress only the local police are involved. Maybe I should consider having my detective call in for help!