The Murders of Mark Harnish & Theresa Marcoux (Massachusetts)

It was one of the most confounding unsolved crimes that the town of West Springfield, Massachusetts, had ever seen. Two young people, shot and killed in their car without any conceivable motive. This seemingly random double murder remained unsolved for over 40 years…Until police received a new tip that finally unraveled the entire mystery and led them to the door of a suspected killer.