Police believe that Eugene Palmer, 73, is still alive somewhere in Harriman State Park in Rockland County, N.Y.
Cops say he has lived near the woods his whole life and knows them really well.
For days from sunrise to sunset, on the ground and now in the sky, police have been searching for Palmer. Now police plan to try to wait him out rather than continue to comb the woods.
"There are so many places to hide," Haverstraw Police Chief Charles Miller said Thursday, the AP reported. "He could be hiding anyplace."
Miller said finding Palmer in the 46,000-acre park is like finding a needle in a haystack.
Palmer is the prime suspect in the shooting death of his daughter-in-law Tammy Palmer.
On Wednesday, authorities flew a helicopter over Harriman but found nothing. On Tuesday afternoon, bloodhounds led police to a fresh campfire. Hours earlier, cops found Palmer's pickup truck in the woods.
Palmer had been arguing with his daughter-in-law about his son's custody rights and disappeared after she was killed. Tammy Palmer is separated from her husband, Eugene's son, and had a restraining order against him.
Although Eugene Palmer has diabetes and heart problems, cops said the skilled huntsman is most likely is still alive.