On December 31, 1975 half of the Mahoney family -- a prominent doctor, his wife and their 15-year old son -- were gunned down in their rural Massachusetts home while quietly ringing in the New Year.

The murders sparked deep fear in the small community and sent a team of local investigators on a winding, six-month pursuit of the killers.

To this day, there are still questions about what exactly happened in that house on Whipple Road.