Tupper Lake, NY, Mar 16, 2012 — More than 120 volunteers combed the woods and water near Tupper Lake again yesterday. They turned up no sign of 18 year old Colin Gillis.

The college student was home for spring break when he vanished early Sunday morning. After four full days of searching, state Forest Ranger Captain John Streiff says the search effort will be scaled back in the days ahead.

While field crews continue to search for clues that might lead to Colin Gillis's whereabouts, state police have also opened an investigation into what may have happened the night that he vanished.

As Brian Mann reports, police are interviewing people who attended a party that Gillis attended Saturday night.