DNA records vs. fingerprinting

One thing I’ve never been entirely clear on is why we should feel terribly nervous about the government having our DNA samples on record. Now, I’m not saying that, at birth, everyone should have blood drawn, analyzed and kept in a database or anything like that. But let’s say you’re accused of a crime, a DNA sample is taken, and you are then acquitted of that crime (possibly because the DNA sample itself exonerates you!). Why should we, as a society, be terribly freaked out that the cops have our DNA on file? How is it any different from them keeping a record of fingerprints? My understanding — and I could be wrong — is that one’s fingerprints are kept on file long after lockup and release. Once you’re fingerprinted, you’re in the system for life.*

I ask because Alex Massive, guestblogging for Andrew, seems quite offended that the British were able to catch a rapist because his DNA had been kept on file after he was acquitted of another attack. A hypothetical: If they had found the rapist’s fingerprints on the wheelchair of the handicapped woman who was sexually assaulted and then matched those up to fingerprints in the database the police maintained, would Alex have the same reaction?

I mean, look: I realize there’s a difference between DNA, “the building blocks of life,” etc. and fingerprints. If the state was keeping a record of our DNA to try and create a clone army or something, I’d be opposed to it. I’d probably be opposed if the police wanted to get everyone’s DNA as well to create some sort of master list. But this seems to be relatively harmless as far as “invasions of privacy” go. The DNA had already been collected as part of a police investigation; there was a database set up to help catch criminals who got away with their crime; the rapist then got caught. What’s the big deal?

*Again, I could be mistaken; if I am, feel free to make note of my ignorance in the comments.