A Metropolitan Police custody sergeant lied at the inquest into Sean Rigg's death, falsely giving evidence that he had checked on the 40-year-old, a court has heard.
Mr Rigg died after collapsing in police custody on August 21 2008. After being arrested, he had been kept in the back of a police van for some time before being taken into Brixton police station, where he fell ill minutes later.
Paul White, 53, is accused of lying while giving evidence at the inquest into Mr Rigg's death.
Jurors heard that in March 2009 White told the Independent Police Complaints Commission (IPCC) that he left the south London custody suite to check on Mr Rigg in the van.
On July 10 2012 he told the inquest at Southwark Coroner's Court the same thing, stating that he had assessed Mr Rigg's health between 7.53pm and 8.03pm.
But Max Hill QC, prosecuting, told Southwark Crown Court that White was "clearly lying".
He added: "Analysis of CCTV footage from the custody suite at Brixton police station proves that at no time did Sergeant White visit Sean Rigg in the back of the police van.
"As you might expect, Sergeant White was confronted with this evidence in the witness box at the inquest hearing, and he conceded that he could not have been to see Mr Rigg as he had described.
"We suggest that Sergeant White deliberately lied in his evidence, in order to conceal the fact that he did not undertake any assessment of Sean Rigg's condition and welfare during the period in which he was kept in the van.
"This is important because, as the on-duty custody sergeant that day, Mr Rigg and any other persons detained at Brixton police station were in Sergeant White's care."
Jurors heard that Mr Rigg had suffered from paranoid schizophrenia for many years, and in the weeks leading up to his death had not been taking his prescribed medication.
Police were called after staff in his supported accommodation became concerned by his behaviour.
He was seen on August 21 bare-chested, wearing only white trousers and trainers, and doing karate kicks on the pavement.
Mr Rigg was arrested by police and arrived at the police station in the back of the van at 7.53pm.
White, who is on crutches after undergoing a knee operation, denies one count of perjury.