A civil rights group says the release of video showing an undercover agent allegedly buying drugs from a man later killed by a volunteer officer is "character assassination."

Tulsa County sheriff's officials released video late Tuesday of a man who allegedly sells drugs and talks about selling a gun to an undercover officer last month.

The sheriff's office says the recordings show Eric Harris, who was fatally shot April 2 by volunteer deputy Robert Bates during a sting investigation. Bates has said he confused his handgun with a stun gun.

Marq Lewis, an organizer with We The People Oklahoma, said Wednesday that police are trying to slander Harris's character, and that video showing an alleged crime doesn't justify a suspect's death.

A sheriff's office spokesman and Harris' family declined comment.