Metropolitan police officers have been accused of a “gross dereliction of duty” for placing a mentally ill man in a potentially fatal position in the back of a police van, an inquest heard.

Sean Rigg, 40, died in the caged area of Brixton police station in August 2008 around an hour after being physically restrained and arrested by four constables.

The officers were accused at Southwark Coroner’s Court of placing the handcuffed Mr Rigg face down in the prone position, with his legs bent back touching his buttocks in the small caged foot well of the police van, which they all denied.

This ‘hog-tied’ position poses a serious risk of positional asphyxia as it restricts a person’s ability to breath, the jury has heard. The risk of asphyxiation is intensified if the person is suffering from acute mental breakdown, has been agitated or restrained for a lengthy period - all of which applied to Mr Rigg.

The four arresting officers, who had already given earlier this month, were ordered back for further questioning after a crucial briefing that took place hours after the death only came to light during evidence two weeks ago.

The jury and the Rigg family only learned of the meeting involving the Independent Police Complaints Commission, Police Federation and Department of Professional Standards after PC Mark Harratt mentioned it during his evidence. An internal memo produced by the IPCC following the meeting had not been disclosed until last week.

The credibility of the officers was questioned by the jury as they tried to make sense of the contradictory evidence they have heard about what happened that night, and from what they have seen on CCTV footage.

PC Richard Glasson was unable to explain why he had told the court the mobile computer in the van was not working when the jury have evidence that information was sent and received that evening.

After several attempts by the jury to understand the discrepancies Leslie Thomas QC asked: “I’m going to suggest to you PC Glasson that the reason there is confusion in the documents is simply because you are lying about the MDT... do you accept that?”

“No sir.”

PC Mark Harratt was accused by Leslie Thomas QC of changing his evidence after being “tipped off” about CCTV footage shown to the jury since his last appearance, which the officer denied.

The four officers were unable to explain why the IPCC has provided a record of facial injuries documented on the night of Mr Rigg’s death, when they had all told the jury that they had not seen any injuries.

Mr Thomas asked PC Andrew Birks: “I am going to suggest to you that you put Mr Rigg in the foot well, in the prone position and that explains the injuries on his face, and because of his height he was put with his legs bent up, touching his buttocks.”

“I don’t accept that.”

“If you had put him in that position it would have been quite wrong...it would have be a gross dereliction of your duty officer, do you accept that?”

“It is a hypothetical question but yes it would have been a dereliction of my duty.”

In another example of conflicting evidence which the jury must consider, Sergeant Andrew Dunn told the jury that he had gone out to the police van in the station yard to check on PC Matthew Forward, who had been assaulted during the arrest, and saw Mr Rigg sitting on the back seat, looking perfectly fine.

About an hour later, PC Forward told the jury that Mr Rigg was in the foot well of the van for the whole time at the station, and he did not recall Sergeant Dunn attending the van or asking him anything.

The officers were also asked to explain the CCTV footage showing their van “blue-lighting” it from the station, swerving to avoid other cars and driving on the wrong side of the road, if as they had previously told the court, they had not seen the urgent police log regarding a 999 call about Sean Rigg “running amuck” on the streets.

All the officers insisted that they had no idea that the man they had arrested was Mr Rigg, known to Brixton police as a man with a long history of violence during psychotic breakdowns, until much later.

Sergeant Dunn, who sent the officers on the job, told the inquest that he had made the link between the man “running amuck”, the man arrested and the man in the van because it was a “reasonable assumption to make.”