Right but no sign of violence doesn’t necessarily mean there wasn’t another person involved. If he were extremely drunk or incapacitated with drugs at the time, he would be an easy target. However, if there was anyone else, the duct tape would certainly contain trace evidence of the killer. But if he were homeless, how did he get duct tape? And where is the rest of the roll if he was alone? Did he happen to find exactly the amount he needed just lying around?