I've been asked that question several times by people interested in submitting. Here's the rundown.
"Fingerprints" is looking for the kinds of stories you've told a million times to a million people. Those crazy, messed up stories that skirt the edges of the law. Fingerprints calls it "crime flash non-fiction." You might call it, "That time we were in that gas station and this guy tried to rob the place with a Super Soaker."
If you've got a story like that, write it up in 500 to 2,000 words and e-mail it to ben [dot] sobieck [at] gmail [dot] com. Make sure "Fingerprints Submission" is in the subject line. Also include a brief bio at the end of the story.