If the person you suspect is a juvenile, chances are his or her fingerprints are not on file and mere suspicion is not enough to bring them in and take their prints. Even if there is a comparison print on file, the time and cost to locate and match it is not justified in a vandalism case. And finally, even if you could lift a print, and match it to someone, the chances of successfully prosecuting them are slim. A good defense attorney would argue that his client had a habit of picking up rocks as they innocently walked along the streets. They would argue that their client's prints are on lots of rocks.
Conviction requires proof beyond a reasonable doubt.
Without a witness you could never prove that they actually threw the rock. District Attorneys get re-elected based on the number of cases their office successfully prosecutes. They don't take on cases they know they can't win. I am very interested in receiving any advice on academic subjects and training that will assist me in professional development in this career field. Specifically, I would be most interested in any type of Distance Learning programs.