Or fingerprints, that kind of thing

I've put the shirt in a ziploc with the air out so it should be basically preserved

i'm not an expert and don't know the actual answer, but have you ever heard of DNA (or fingerprints lol) being found on a shirt? or even anyone looking for dna on a shirt?

IF you find a hair on the shirt, you might get dna, but that won't prove anything other than somehow a hair with that dna landed on the shirt--doesn't prove it was the person wearing the shirt or when that happened

DNA on a shirt is definitely possible - hair, skin flakes, possibly even body oils, but fingerprints? No, not getting a fingerprint off of a textile unless the finger was dipped in something first.