A retired FBI agent has weighed in on the search for 84-year-old Nancy Guthrie, offering her insight into how investigators might be able to crack the case.

Jimmy Gracey's death calls may prove as difficult to solve as a missing person case from years earlier.

“I think the number one way this case is going to be solved is somebody coming forward that knows him," former FBI agent said.

For nearly five decades, the mysterious disappearance of Peter Adams, who was just 20 at the time, went unsolved.