A man will go on trial for attempted murder in Brooklyn. His fate may hang on the handlebars of a bicycle.

Prosecutors contend he shot a man from the bike, and may have left a DNA calling card on its surface. He may not have been the only one to touch the bicycle, though.

As DNA evidence is increasingly used in courtrooms, forensic scientists are struggling to find more-precise ways to analyze smaller and smaller samples that contain multiple contributors — scraped from, say, the trigger of a gun, the handle of a knife or the trim of a scarf.

Two scientists at the forensic biology laboratory of the New York City medical examiner’s office have created a way. The scientists, Theresa A. Caragine and Adele A. Mitchell, produced the Forensic Statistical Tool, an algorithm for a software program that can analyze a mixture of DNA from a crime scene and determine the probability that it could include the defendant’s profile.