A device used to record bin weights on the lorry that visited the area where Corrie McKeague was last seen was reset the day before it was collected by police, an inquest heard.
The RAF airman from Dunfermline, Fife, was 23 when he disappeared in the early hours of 24 September 2016 after a night out in Bury St Edmunds.
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.
Waste firm Biffa initially told police that the weight of the bin was 11kg (1st 10lbs) but it was later recorded as 116kg (18st 3lbs).
Det Con 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 1 February, 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 29 September, and the following day changes were made to Biffa's 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.
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.
"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.
Det Con Morgan said that in 2018 officers filmed the bin lifting process on the lorry and recorded that it took 40 seconds from the bin being attached to the lorry to it being tipped and returned to the ground.
The inquest, being heard with a jury, continues.