REOPENED: Officer Down

A police lieutenant goes into his kitchen to get a snack, then his wife hears shattering glass and finds her husband has been killed. He was shot in the back of the head. Lt. Joe Clark was a beloved member and protector of the community. So who would want him dead? Was it related to the drug rings he relentlessly pursued? What could police learn from the shotgun shell recovered at the scene? And what does it all have to do with a blue Ford Pinto?