The five-year hunt for a missing man who was feared murdered was "the one of the most unusual cases I have ever led", the detective who found him said.
Ricardas Puisys, 35, vanished without a trace from his home in Wisbech in Cambridgeshire, in September 2015, sparking a police murder investigation.
The case will feature on the Channel 4 programme 24 Hours in Police Custody.
Evidence of the "dark world of modern slavery" was uncovered before Mr Puisys was found in August, hiding in a wood.
Supt Adam Gallop from Cambridgeshire Police said: "While I always hoped we would find Ricardas alive, all the evidence led us to believe it was highly unlikely."
The last confirmed sighting of the Lithuanian national was at his workplace, Nightlayer Leek Company in Chatteris, on 26 September 2015.
Detectives feared Mr Puisys might have been the victim of a serious assault in the hours before his disappearance.
A man was arrested and released, but no trace was found of the missing man.
Supt Gallop said: "Given the fact no-one had seen or heard from him, our searches were focused on looking for his body and those responsible for his death.
"He had literally vanished and no-one ever saw him again."
The lengthy investigation uncovered "disturbing details about the dark and dangerous world of modern slavery".
Then in November 2019, a Facebook account was set up in Mr Puisys' name.
At the end of June last year, officers received information which led to them to search a wooded area of Harecroft Road in Wisbech.
Mr Puisys was found living "well concealed" in undergrowth.
Supt Gallop said: "This was one of the most unusual cases I have ever led.
"When we found the Facebook page it gave us hope, but it still took time and a great deal of good detective work to discover the truth behind Ricardas' disappearance and finally locate him."
The episode of 24 Hours in Police Custody will be broadcast on Channel 4 at 21:00 BST on Monday.