This is the last post in my Forensics series for this A to Z Challenge. I’ve had fun with these and I hope they’ve helped you identify some elements of plot you could include in your novels, whether they be in the crime genre or not.
Dr. Edmond Locard, a forensic science pioneer, had a theory that became known as Locard’s exchange principle:
“Every contact leaves a trace.”
Unless you move around in a fully protective space suit, you’re likely to leave trace evidence wherever you go. Be it, fingerprints as you open doors, or handle a glass for your drink, or the impressions your feet leave walking across a freshly weeded garden.
What if you then went into someone’s home and deposited the soil on their kitchen floor. You could have also walked through a freshly painted floor and a combination of the two are left in the kitchen. When the police arrive to investigate the case of the stolen cookies, you are likely to incriminate yourself through the trace on your shoes.
And, if your cookie stealing, mud spreading villain broke a window to steal those delicious treats, then they could well have glass shards caught in their clothing, footwear and about their personage. Whilst most of these fragments would work loose within hours, it could still be an avenue for your detective to investigate.
When the case is slightly more serious than stolen cookies, and a struggle, possibly violent struggle has taken place then other evidence will be left behind. One of the most common will be hair.
As well as the possibility of obtaining a DNA sample, hair can be examined to show the species it originated from. That walk in the park with the dog, could be a pointer to whodunnit in your novel, so could the cat hairs deposited from around your criminal’s ankles where their cat rubbed up against them waiting for breakfast.
You also have other fibres. The most common one will be either clothing or carpets. Did your killer put their victim in the boot of their car? Well fibres from the boot are likely to be present when your detective finds the body. That and the blood traces found inside the boot will take some explaining.
If every contact leaves a trace then think about how your criminal arrived at the scene, what interaction they had whilst they were committing the crime and what they could have left behind for your detective and crime scene characters to find.
I hope these posts have stimulated some crime writing ideas for you or things to think about when you decide to break the rules and go for that extra cookie in the middle of the night. 😉
Happy Crime Writing!
This is my U post for the A to Z Blogging Challenge. A list of all my A to Z Blogging Challenge posts are to be found here.
Today my photographs are from Universal Studios L.A from back in 1990.