RAF gunner Corrie McKeague "probably wouldn't have known much about it" if he were asleep in a bin which was tipped into the back of a waste lorry and died, an inquest has heard.

The airman, from Dunfermline, was 23 when he disappeared in the early hours of September 24, 2016 after a night out in Bury St Edmunds, Suffolk.

He was last seen on CCTV at 3.25am entering a service area behind a Greggs store and police believe he climbed into a bin which was then tipped into a waste lorry.

Suffolk's senior coroner Nigel Parsley asked consultant forensic pathologist Dr Nat Cary about possible causes of death if a person were to end up in the back of a bin lorry.

Dr Cary told the inquest in Ipswich: "The most obvious cause of death in those circumstances would be crushing.

"That refuse lorry is designed to crush and compress refuse.

"If an individual came into the chamber then crushing would be a likely possibility.

"Over and above that, multiple injuries - head injuries, injuries to the limbs."

He said there could be the "same effect you get in a crowd crush", adding that suffocation was also a possibility.

Dr Cary said there was a "not impossible, remote" chance that someone asleep while intoxicated in a bin could get positional asphyxia and die before the bin was tipped.

He suggested a possible cause of death in circumstances where a person is tipped into a bin lorry as compression asphyxia in association with multiple injuries.

Dr Cary said if a person were intoxicated "it would prevent someone being able to take evasive action if someone was in a bin that was then tipped".

He added: "I would expect a conscious, sober person to have real difficulty.

"I should probably say, he probably wouldn't have known much about it if that's what happened."

Dr Cary said it was "hard to think that someone could survive" if they were tipped into the back of a bin lorry.

Asked how quickly a person may fall unconscious, he said: "It does depend on the level of compression, which is an unknown, but given the levels of force involved in this lorry I would expect unconsciousness would occur quite rapidly within a few minutes."

He said a medical cause of death of "unascertained" can be recorded when a body has not been found.

The inquest also heard that a device used to record bin weights on the bin lorry that visited the area where RAF gunner Corrie McKeague was last seen was returned to factory settings the day before it was collected by police.

Waste firm Biffa initially told police that the weight of the bin was 11kg (1 stone 10lbs) but it was later recorded as 116kg (18 stone 3lbs).

Detective Constable Richard Morgan told an inquest in Ipswich that an electronic device, kept in the cab of the bin lorry and used by the driver for bin weights, was returned to factory settings the day before it was collected by police, on February 1, 2017.

Data from the device is downloaded to the database of waste firm Biffa after a lorry completes its rounds.

Lawyer Dr Anton van Dellen, asking questions on behalf of Mr McKeague's father Martin McKeague, said: "Concentrating on that wiping of the (device), as a detective constable in a major investigation team, you're going round collecting evidence for an investigation.

"You've found that somebody has effectively wiped the (device) of electronic information that as far as you're aware they're fully aware you wanted to look at.

"What view, if any, did you take about how suspicious that action was?"

Det Con Morgan replied: "I thought it was highly suspicious.

"It was quite clear why I wanted it.

"By wiping it, it put that data beyond use.

"Someone at the Biffa depot did this."

He added that police later learned that the data stored on the device would have been of "no evidential value to us" anyway, adding that it was "ludicrous" that somebody had performed a hard reset.

The correct bin weight, of 116kg, was provided by senior staff at Biffa who got the firm's IT experts to examine raw data in the database.

The inquest heard that bin lorry driver Martyn Thompson was first spoken to by police on September 29, and the following day changes were made to Biffa's front-end facing IT system Biffanet so users would see the weight as 11kg.

This did not alter the weights in the database underpinning it, which could not be seen by users of Biffanet.

Det Con Morgan said two staff from the Biffa depot in Bury St Edmunds, who were not named, were interviewed under caution on suspicion of perverting the course of justice and were later told they faced no further action.

Bin lorry driver Mr Thompson was never a suspect in the investigation.

Det Con Morgan said that one of the individuals said when interviewed that Mr Thompson had asked for "reassurance" about the bin weight.

"When I interviewed one of the individuals, what they said was he (Mr Thompson) was having self-doubt about whether the bin was heavy enough," said Det Con Morgan.

"He wanted reassurance the bin wasn't heavy enough and he was given that reassurance."

Mr Thompson earlier told the inquest he checked the bin and did not see anybody inside it.

The inquest, being heard with a jury, continues.