Do you know the difference between finger prints, finger marks, latent and visible prints or what friction ridges are? I have just completed the module on fingerprints as part of the Introduction to Forensic Science MOOC which I am studying through FutureLearn. It’s so important to get these details correct when writing a crime novel. Unless you have a novel set more than 100 years ago, it’s probable that the police investigation of your crime will involve forensics, and one of the most established worldwide is the taking and comparison of fingerprints. So some definitions: fingerprints are from known sources eg when you have your prints taken either as a suspect or to eliminate you from an enquiry; however fingermarks are from an unknown source eg they are found at a crime scene. In some countries, these are called latent prints so do check the local terminology.  And the difference between latent and visible prints is in the name. Enhancement techniques such as powders are needed to make latent prints become visible. Both are photographed (or transferred to tape) and added to a national database of prints, and a computerised system used to compare prints. If you want your detective protagonist to take prints, it’s easy. Use a pencil to cover a patch of white paper and roll your fingertip across it. Then place this on the sticky side of clear sellotape and stick that onto white paper. The result is remarkably clear. Happy writing 🙂