New Orleans police say an officer now facing criminal charges failed to thoroughly search a suspect who later allegedly shot another officer to death in a police car.

Chief Michael Harrison said Tuesday that suspended officer Wardell Johnson also avoided collecting and processing evidence when suspect Travis Boys was arrested over an assault. Harris says that among that evidence was a spent shell casing from a .40-caliber handgun.

Hours later, officer Daryle Holloway was killed. Officials say Boys shot him with a .40-caliber gun on June 20, shortly after the arrest. He has pleaded not guilty. Police say they remain uncertain about how Boys obtained the gun.

But Harrison says Johnson's pat-down search of Boys was not thorough and not in keeping with police training.