The ballistics tests determined that the bullet that killed Ms. Gay, from a 9-millimeter gun, had markings consistent with those made by seven manufacturers’ guns, including [b]Glock .

It was doubtful whether the source of the shot that killed Ms. Gay would definitively be determined, even by comparing the slug to those from the Glocks fired by two officers, the police said, because of the generic markings the lead slug picked up as it passed through the gun’s barrel. Also, the round retrieved from Ms. Gay’s body was deformed.