Finding Michelle Welch’s Killer (3:07)
Nowadays, detectives are able to rely more and more on science to help solve crimes. With advancements in fingerprint and DNA technology, as well as the emergence of large databases filled with genealogical information, as long as there’s some evidence a human was at a crime scene, it’s possible the police can figure out exactly who it was. Here are some things detectives may look for when a crime has been committed:
While fingerprints do not contain DNA, every single fingerprint is unique. The same person doesn’t even have the same two fingerprints on each of their fingers! If the police find a fingerprint at a scene, they may run it through a database to see if it matches up with any known fingerprints to figure out who it belongs to. In one study, forensic fingerprint technology was so accurate it only missed attributing a fingerprint to somebody it should have 7.5% of the time.
Hair itself does not contain DNA, but the hair follicle at the base of the hair does. This means if detectives find a whole piece of hair at a crime scene, they may be able to get a DNA sample of the person the hair came from. They could then run this sample through a database of known DNA to see if they get a match.
Blood, saliva, and other bodily fluids are also filled with DNA, which means if the police find some of it, they can start trying to figure out exactly who the culprit is. Like with hair DNA, they could run this sample through a database to see if there are any matches.
Unlike what it might look like in television shows, the police don’t have a file of everybody’s DNA. This is why new companies that keep DNA genealogy records are so important. Even if you haven’t submitted your own DNA to a genealogy company, it’s possible some of your relatives – even distant ones – have. And because your DNA is similar to the DNA of others in your family, the police may be able to find “partial matches”. They could then identify who a suspect’s family is, narrowing the scope of their investigation.