Stewart Robertson, 50, told officers that he knew where to find the remains of Mark Manning.
Mr Manning, a 54-year-old father of two, was last seen in April 2014 as his friend Colin Gale told police that he had dropped him at Worthing railway station.
However there was no CCTV footage of Mr Manning at the station and no reported sightings of him.
Instead, Gale, 40, had killed Mr Manning at a garage that he ran in Lancing, because he could not pay the ex-bomb disposal expert back the money that he owed him.
Colin Gale (L) and Stewart Robertson (R)
Gale’s associate Robertson then helped Gale dispose of the body the following morning.
Gale was found guilty of manslaughter and he admitted preventing a lawful burial. Robertson was found guilty of preventing a lawful burial, with sentencing later this month.
In the footage, Gale can be seen telling defectives where to find the remains of Mr Manning who had worked for the Mines Advisory Group, a charity that removes landmines in some of the world’s poorest countries.
He said: “I’ve been told where his body might possibly be and I am wiling to take you there as far as I can remember.
“I can’t guarantee that the body is there because I don’t know, I have never seen it but I have been told that it is in a certain place.
“I would have to show you it’s along the A24 and off of the A24 out in the, and there’s a lake and a garage, are close to it, that he uses.”
Mark Manning's remains were found after Robertson told police where they were
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They clung to the hope that Mark would one day walk back into their lives
Detective Chief Inspector Mike Ashcroft
Extensive work was carried out to recover and identify the body as Mr Manning, as dental records revealed it was him.
A post mortem showed that Mr Manning had suffered severe head and facial injuries when he died.
During the trial Gale confessed to his wife that he owed Mr Manning £150,000, and when he turned up at his garage they rowed about it.
Gale said that Mr Manning came at him with “something” which he grabbed off him and hit him over the head with it.
Detective Chief Inspector Mike Ashcroft, who led the investigation said: “This has been a long and complex investigation and my thoughts and condolences remain with Mark’s family and friends who have waited a long time for answers and for closure.
Mark Manning was killed after he had had suffered sever head and facial injuries
“He has put Mark’s family through a living nightmare.
“They clung to the hope that Mark would one day walk back into their lives. However Colin Gale knew that would never happen.
“He did not tell anyone what he did with Mark’s remains despite having many opportunities to do so. He not only killed Mark but destroyed his family’s lives as a result.”
Mr Manning’s son Kane, 18, added: “My father was a hero, he saved many people's lives around the world with his mine clearance work.
“I had an amazing bond with my father and I find it hard knowing my dad will never be around to see me grow up. I am so glad that justice has prevailed in the end.”
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