It has been 16 days since Gabby Petito's fiancé, Brian Laundrie, allegedly told his parents he was going for a hike in a sprawling Florida nature preserve. He hasn't been seen since, despite scores of law enforcement searching the unforgivable terrain in what has become an all-out manhunt for the FBI's prime person of interest in Petito's disappearance. Why? At least one seasoned investigator, a retired federal marshal with three decades of experience searching for -- and finding -- people who were on the run, says he doesn't think Laundrie was ever in the Carlton Reserve in the first place. On this week's Debrief, Craig Caine, who supervised members of the New York/New Jersey Regional Fugitive Task Force before his retirement from the U.S. Marshals Service, said he believes Laundrie was never in that nature preserve at all.