Obscuring Blood Evidence with Ammonia

Factual Questions
1

I saw “Boondock Saints” on DVD yesterday. At one point, a main character is shot in a gunfight and sprays what is later revealed to be ammonia on the blood splatter.

Later, an FBI agent played by Willem Dafoe smells the ammonia when investigating the scene and overacts - I mean “reacts” - to it by declaring that the blood evidence is now worthless. This is BS, right? If we can get DNA from fossilized animal matter, a little ammonia ain’t going to stop us. Any Dopers know the real deal?

2

Anyone? Bueller?

3

Ammonia does react with ninhydrin, so it could interfere with simple tests for blood proteins by producing a false positive. Ammonia will not destroy DNA, and there are many tests for blood and blood proteins that it will not affect.

4

I don’t have anything to say other than I love that movie, except when I mention it nobody has ever heard of it.