acting as richard matt's accomplice in that 1997 murder. he testified against him. and in a phone interview with anderson cooper called matt evil. >> if you wanted to take a picture of the devil, that's the face that you would see. >> bates remembers matt shoving a knife sharpener in his victim's ear and breaking his fingers before killing him. >> i have seen him kill. he did kill mr. rickerson, his old boss, in my presence. in a fit of rage he reached into the car, grabbed mr. rickerson by his head and snapped his neck in front of me. >> matt worked for rickerson and was fired for poor performance just weeks before rickerson's murder, according to testimony at trial. >> i don't understand that. >> eric jensen knew both richard matt and david sweat. he served nine months in clinton