milk carton he vanished in 1979. in 2001 declared legally dead, remains never found. tonight, though, just blocks away from his home in manhattan s soho district, police and fbi agents believe they re on to something. susan candiotti is there for us. what do you know? reporter: law enforcement sources tell me that they came here based on new and old information that led them to a man. a man who is now in his mid-70s. but at the satime he was a car carpenter and and befriended the boy and given him a dollar. we don t know the circumstances how this came about, in fact this informatiled authorize int basement picking up a human scent, bringing in a team of investigators certaining the ba searching the basement all day long. basically tearing the basement apart, i imagine? reporter: they are. in fact, they also don t have this man in custody, but they know who he is and where he sand are in contact with him. they re using jackhammers. set up in the grids a cement floor, ta