The charge, from the US District Court for the Western District of Missouri, accuses Detective Scott Coates, 42, of allowing a man with prior convictions keep a handgun even though he was prohibited from possessing a firearm.
Coates interviewed Corey Barr after a gang-related shooting in 2007. According to court documents, Barr brought a handgun with him to the interview and let Coates photograph it.
After the interview, Coates allegedly allowed Barr to leave with the gun.
A superior to Coates later ordered that the detective find Barr and get the gun. He did so, but allegedly booked it into evidence more than 20 months later. The gun was eventually returned to Barr. The indictment states that Coates "caused the Smith and Wesson .40 caliber handgun" to be returned to Corey Barr.
Barr was arrested again in 2010 in possession of the handgun. He pleaded guilty to illegally possessing a firearm.
Coates, a 20-year veteran of the department, is now charged with aiding and abetting possession of a firearm by a prohibited person.
According to Police Chief Chris Connally, Coates has been placed on non-duty status with the department, which is unpaid, as he awaits a court hearing on Thursday.