Video report by ITV News Anglia's Serena Sandhu
A former detective has told ITV News Anglia he believes a third party was involved in the disappearance of RAF serviceman Corrie McKeague - who has now been missing for a month.
Colin Sutton was a senior detective for the Metropolitan Police, overseeing cases such as Milly Dowler's disappearance and subsequent murder. He retired from the force five years ago.
He does not believe that Corrie intentionally disappeared.
The known sighting of Corrie is CCTV footage of him walking down Brentogovel Street at 3.25am on 24 September after a night out in Bury St Edmunds.
Colin thinks it's "unusual" that he evaded a number of CCTV cameras in the area.
Corrie sent a text message just after 3am on the night of his disappearance.
The phone was switched off hours later at Barton Mills around 13 miles away. It coincides with the movements of a bin lorry seized by Suffolk Police.
Despite extensive searches of the area, nothing has been found.
Corrie's family are actively trying to help detectives search for him, but there are still many unanswered questions.
Police have the ongoing task of finding the missing pieces to the puzzle to explain how a 23-year-old could seemingly vanish without a trace.