It is 500 days since missing airman Corrie McKeague was last seen in the early hours of a Saturday morning in Bury St Edmunds.
The RAF man, who was based at Honington, Suffolk, was last seen on CCTV in the early hours of September 24, 2016, at 3.25am.
Footage showed Corrie entering an area of rubbish bins behind shops, known as the 'horseshoe'. He has not been seen since.
£2 million has been spent on the investigation so far, and what happened to the RAF gunner remains a mystery.
Police believe Corrie may have climbed into a bin to sleep before being taken away by a refuse collection lorry, sparking two searches of a landfill site at Milton.
They spent 27 weeks trawling through 7,000 tonnes of rubbish, but nothing was found.
Speaking to Forces Network at a charity rough sleep event, Corrie's uncle said the family now believes he could possibly have walked out of the horseshoe area undetected by CCTV.
Tony Wringe (Corrie McKeague's uncle): "We now question whether or not it was possible to walk out on foot, undetected by camera."
Over the months since Corrie disappeared, hundreds of volunteers have joined professionals on regular searches across the area.
The police have always rejected claims that they’ve failed to follow up leads, but Corrie's uncle Tony Wringe says the family has been undertaking its own investigations, and continue to do so:
"500 days later, he could still be there."
"He could have walked out, and he certainly could have left in a vehicle - which is exactly where we were nearly 18 months ago."
However, a Suffolk Constabulary spokesman said:
“An independent review of Suffolk Constabulary’s inquiry into Corrie McKeague’s disappearance has shown the investigation to have been professional, thorough and diligent.
"The Major Investigation Team has also continued to ensure all realistic lines of enquiry have been rigorously explored.”
There is now a £100,000 reward on offer to persuade anyone with information on Corrie's disappearance to come forward.