How long can fingerprints survive indoors undisturbed?

The thing with hair though.... don't you need the root to get definitive DNA? In other words, it has to be pulled out, rather than just dropped.

Has the house sat empty for 25 years? Why?

If not your going to have to come up with a really good and "neat" place for them to look for prints that much later.

Why wouldn't they have looked in that spot in the first place and why did they think of it now?

Off the top of my head the first thing that comes up is maybe there was a remodel/renovation done by the new owners that revealed a walled over part of the wall or some small space that was closed up in the past (like a small closet or something). But, if it was accessable at the time of the crime, why didn't the investigators look there earlier?

As to if prints would last fro 25 years, a quick Google seems to indicate "Maybe." Do some research on what surfaces hold prints the longest and if you work that type of surface into the story it might work.

There's also the "it's not a finger print, it's a finger impression" idea. Something like a print in wet plaster or wet cement that wouldn't degrade because it's actually an impression that doesn't rely on skin oil. The investigators could take a photo or make a mold or something to get a copy of the print/impression.

The idea of a impression left in wet stucco, plaster, etc, leads me back to some renovation or deliberate hidden room/hidden space that wasn't known about at the time. Maybe the first investigators didn't even find it because it was hidden, but a new renovation revealed it.

No idea if any of this works in your story though.

Your best bet would be blood. It's nearly impossible to get rid of blood on an organic or remotely porous material, unless you remove the material it was on.

Prints in wet paint will last. Though it's doubtful anyone will ever run forensics on a quarter-century-old crime scene.

Jeff

The problem with fingerprints is that they're the result of body oils and sweat which are organic. Typically they're going to break down before your 25 year deadline. For a fingerprint to last that long it needs to be imprinted in something else. Blood was mentioned here. I think that ink/dye or even wine would work equally well. The problem is that these are all extremely visible items. You'd need to hide the fingerprint extremely well if it's uncaught for 25 years.

People absolutely run forensics on old scenes, for a variety of reasons. Either people didn't know the scene was involved, found new information that sent them to it or back to it, or sometimes go back specifically to see if there are forensics that can be run, sometimes a scene is discovered in situ that people didn't realize was actually a scene.

I didn't mean blood to preserve a print, just btw, I mean blood as evidence at the scene. A fingerprint isn't impossible, but there'd be issues with degradation, dust, elimination prints, etc., etc.

I was thinking the "finger impression" thing too. Skin oils will absolutely degrade over that period of time, even if the house isn't lived in. Ideally you'd have a fingerprint in a soft surface which is then sealed off from dust and debris (or at least on a vertical surface). Ideas off the top of my head: caulk, lip balm, or fresh paint (in an out-of-the way place like the inside of a closet). If it's something obvious (like opening Grandma's 25-year-old lip balm out of curiosity and seeing a big fat thumbprint in there), you have a much more plausible reason for your characters to have found it, rather than "We decided to fingerprint the house top to bottom on the off-chance there was something there."

Wouldn't police run forensics that they didn't have at the time on an old scene, if it's still intact?

L.C. Blackwell said:

That is, without being degraded past identification. We're talking a time lapse of 25 years, in a residential home. A cold case if ever there was one.

Most surfaces, of course, would be disturbed too frequently. Doorknobs, windows, etc. Prints would have to be in some out-of-the-way corner, perhaps on a wall or duct work. I would be concerned about them being obscured by dust.

But on the theory that prints ever existed in the first place, and hadn't been obliterated by contact--might an investigator find them?

Or, if he were lucky, some kind of remaining DNA? Hair, possibly, since I assume skin flakes would have long crumbled to powder.

Thanks for any help!

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This part makes me think that people are actively living in the house. If that's the case there isn't any change you'll be able to get a team to go in there looking 25 years after the fact. Detectives get pissed enough as is just having one unauthorized person walking through a crime scene and tracking foreign material through it.

Your best bet would be having the "residents" making some form of renovation and then finding blood spatter under a rug or something. Someplace that the officers didn't look 25 years prior.

(Someone picking up a melting candle could leave a wax fingerprint though... but I don't know why anyone committing a crime would even consider doing something like that.)