I watch those crime shows sometimes and they are always showing the use of Luminol. I know it detects if blood has been on an area, but does it determine whose blood it was?
For example, I am in my bathroom and happen to cut myself badly. I spill my blood all over the floor. I bandage myself and clean up the mess.
Years later, we move out.
The next people who move in, a young couple, are known for their knock down, drag-out fights. The woman leaves, but no one can find her. Neighbors suspect the husband has committed foul play, etc. Investigators, looking for something, use Luminol and come up with my previously spilled blood. Can they tell it’s my blood, or will this man be falsely accused of murdering his wife in the bathroom?
(I know, I know, a little melodramatic, but I’ve been watching too much Forensic Files)
From what I’ve heard (which admittedly comes from those same crime shows on TV) luminol reacts with a protein in the blood, which means it doesn’t discriminate between one person’s blood and another. As far as I’m aware, you need to do a DNA test to figure out who’s blood it is.
From what I’ve seen on those crime shows, hitting someone with an object creates very particular blood spatter patterns, which is how they would be able to determine if you cut yourself shaving and were doing the traditional pain dance, or if Fred offed Wilma in a fit of passion.
No, luminol will not tell you who’s blood it is, or even if it’s human. Luminol will react with minute traces of blood and glow under blue light so you can see it. It will also produce light when reacted with other substances too, so further testing is required. DNA tests such as PCR (polymerase chain reaction) will give you the genetic info you need to see who’s (or what) blood it is.
The only way the husband will get falsely accused or convicted is by… well he couldn’t unless everyone - including his own lawyer - were out to frame him. Also I’m not sure how long a blood stain will hang around… years is pretty long to wait, and bacteria, bugs, and all sorts of stuff may well degrade or completley remove the stain altogether… it depends on the “storage” conditions of your stain and what it’s been splattered onto.
Do a search using the terms luminol, DNA, blood, human and so on to get more than you want to know about the subject.