Perhaps a bit of an odd question, but I was watching a fictional crime TV show with my mom, and the murderer was trying to frame someone by getting their fingerprints on an item and then putting it in a place where it could be “innocently discovered.” And of course, this worked and the protag detective had to figure this all out and fight for the innocent person and exonerate them.
But I started to wonder if this actually would even work, mostly because I’m not sure fingerprints would be so resilient If a real life object were to be treated as it was. So I thought let’s ask some experts and science-minded forensics enthusiasts about the possibility.
In the show, the innocent person touched a metal adjustable wrench (picked it up and tossed it closer to someone; didn’t grip it or hold it with force). Someone then used a plastic bag to gingerly pick up the wrench, which sounds good to me, and would likely maintain the fingerprints as well as can be expected. (The murderer then got the wrench.)
But then, the murderer buried the wrench underneath some dirt in an obvious location where it would attract attention, after handling it with wool gloves and putting it in the pocket of her wool coat. Here’s where I question how well the fingerprints would have held up.
I feel the wool gloves—even if the murderer had been careful not to handle the wrench more than necessary, but she is solidly holding it at several points, and right where the fingerprints would be—would have messed with the fingerprints, since wool can interact with oils and would cause a bit of surface friction when interacting with the wrench. Same for putting it into and pulling it out of the wool pocket, though to a much lesser extent.
The wrench was then put into a hole in a garden, with dirt pushed on top and then tapped down under her foot to compact it. Again, I feel like this too would have damaged whatever prints were on the wrench, from the actual dirt being placed on it and pushed down, but also from the microorganisms present in dirt (and the garden was shown to be a nice one with lots of healthy, thriving plants, so the soil biome was certainly a good one).
Lastly, a short while later, the wrench was dug up by a dog (but the dog barely touched it, more interested in the treats also buried on top of it), and the dog’s owner pulled the wrench from the soil. Now, I don’t think the person brushed the dirt off—which would be another thing that could damage the prints—but still, pulling the wrench out of the compacted dirt and then gripping it all over with their gloved hands—leather/pleather, I think—should have caused even more deterioration of the prints.
So, my question is: after going through this series of events, would it be highly likely that readily identifiable fingerprints would still be on the wrench and there’s some plausibility, or is this some Hollywood bullplop for the sake of a make-the-detective-look-good story? Am I right in thinking that at each stage of this “frame an innocent” plot, the way the wrench was handled would have made it less and less useful for fingerprinting from?
(And yes, this assumes there were decent prints on it from the innocent person just picking it up and tossing it closer at the start of this plot, but I think that, at least, is a reasonable assumption. Although the cops in the show probably should have looked at the orientation of the fingerprints, which would have shown the innocent person didn’t use the wrench in the correct way for him to have used the wrench to match their assumptions.)