Questioning the credibility of two Evanston police detectives, a federal judge suppressed a firearm found in a car the men searched after purportedly smelling marijuana.U.S. District Judge Matthew F. Kennelly on Monday granted Elijah Murphy’s motion to quash his arrest and suppress all evidence seized in the warrantless search of the vehicle.In a ruling from the bench, Kennelly found the testimony of detectives Luis Velez and Jason Kleinpaste about the alleged odor of pot was not credible.The two had given that …