An investigation is underway into the death of a 6-week-old infant in the town of North Salem.   New York State Police were called to the Raymond Road home on Friday on a report of an unresponsive boy.  Troopers responded with North Salem Ambulance and Westchester County EMS.  State Police say the victim, Mason Cowan, was transported to Danbury Hospital where he was later pronounced deceased.  The investigation is on-going.