The Cosby Case's O.J. Problem

Prosecutors in the Ennis Cosby murder trial, scheduled to begin opening arguments this week, have an evidence problem eerily reminiscent of the O.J. Simpson case. At issue is a single human hair, roots intact, that was found in a knit cap wrapped around a .38-cal. revolver connected with the murder. Ballistic tests suggest that the bullet that killed Cosby came from that gun, and DNA testing links the hair to Mikail Markhasev. One problem: when the LAPD's lab technicians inspected the cap after it was found in March 1997, they found only "shed" hairs without roots; reliable DNA testing requires the root.

Nine months later, after it became clear that the case would depend heavily on witnesses with criminal pasts or shaky memories and that physical evidence linking Markhasev to the murder weapon was sorely needed, the cap was checked again. This time, technicians found a single, rooted hair, one that matched the defendant's with a probability of 1 in 15,000. "The obvious argument will be that the police planted the hair or at least screwed up," says a source close to the case, recalling similar moments in the Simpson trial. "It's dynamite."