Nicola Urquhart said police must investigate if her RAF gunner son was deliberately drugged in a club last September

The mother of missing airman Corrie McKeague has said his drink could have been spiked on the night he disappeared.

Nicola Urquhart said police needed to investigate the possibility the 23-year-old RAF gunner was deliberately drugged in a club last September.

The 48-year-old, who is a police officer in Scotland, said CCTV footage showed her son leaving a club and passing out in a doorway before he disappeared into an alleyway.

Detectives fear he was taken from the 'Horseshoe' area in Bury St Edmunds, Suffolk, to a rubbish tip after his mobile phone signal matched the movements of a disposal truck.

Police search teams who have sifted through more than 6,000 tonnes of rubbish at a tip 13 miles away in Milton, Cambridgeshire, continue the search for him.

His 21-year-old girlfriend April Oliver announced the birth of their baby girl Ellie-Louise on Father's Day.

Missing RAF serviceman Corrie McKeague was last seen on CCTV footage on Brentgovel Street in Bury St Edmunds, Suffolk, after 3am on September 24

After reading a Facebook post suggesting Corrie may have been drugged, Nicola said: 'This is possible.

'We need to find Corrie to follow that line of inquiry.

'I have watched the CCTV of Corrie in the doorway.. From him walking in to leaving.

'Every single second. When Corrie slept in the doorway it wasn't because he was looking for somewhere to sleep.

'He slide down the wall he was leaning on. Then fell over on his side. It wasn't what looked like a conscious decision.'

Police investigating his disappearance search Milton landfill site near Cambridge

Pictured: The recycling centre just as the search for the missing man was beginning

The CCTV footage showed Corrie wandering alone in the town centre, which is eight miles from his base at RAF Honington, after being ordered out of a club by a bouncer.

'Corrie looked confused that he was asked, but left with no problems at all,' Nicola told the Sunday Mirror.

Corrie, from Dunfermline Fife, was seen at a take-away before falling asleep in a doorway and disappearing behind a branch of Greggs.

She added: 'I've cried my heart out and been so broken I didn't think I could carry on.

Pictured left: April Oliver, the girlfriend of missing Scottish airman Corrie McKeague (right), holding their newborn daughter Ellie-Louise who was born in June

'But I've also laughed and enjoyed times with my family. I don't believe there is a wrong or right way. I just do what feels right for me, my sons and my family each day.

'I have the most beautiful little granddaughter who is such a blessing.

'And I am still so much more fortunate than some. I don't believe in feeling sorry for myself.

'That won't find Corrie. Like any parent. My children are my world. It's simply not an option to give up.'

Corrie's girlfriend, April Oliver, 21, gave birth to their daughter, Ellie-Louise on June 11 and announced the birth on Father's Day.