We will see hundreds of fingerless, toeless, earless corpses turning up, just coincidentally, right before the Servicemen start wearing body parts talismen.

Let them sew what's left into pigskins before burial.  No Virgins for them.

Hair samples only work if you preserve the little bit skin that attaches the hair to the scalp. That is where the DNA is contained and not in the hair itself. A big bag of nothing but hair would be difficult to keep track of since it could be contaminated by the hair of our servicemen, or you might lose some, etc.

Blood smears might work but also difficult to tell who they came from.

The finger is kind of an "accountable" means of extracting DNA. It's not like you'll have fingers from alive guys accidentally getting mixed in. And when you find the one you want you have something tangable to hold onto and say "This finger right here was removed from a dead guy and that dead guy was Osama Bin Laden."

It sounds a little more believable than: "This single strand of hair I hold in my hand came from Osama Bin Laden and we got it off his dead body."

Just my $0.02. [:D]