The trial of former Metropolitan Police sergeant Paul White delivered a not guilty verdict on Tuesday.
White had been accused of perjury in relation to evidence he gave at the inquest into the death of Sean Rigg.
Sean died at Brixton police station on 21 August 2008.
The trial at Southwark Crown Court heard how White claimed that he had checked on Sean while he was being held in a van in the yard of Brixton police station.
White made this claim three times, at two separate IPCC interviews in 2009 and then again at the inquest in 2012.
At the inquest he was confronted with CCTV footage that showed his claims were not true.
These facts were agreed by both the prosecution and the defence.
The defence case rested on White’s inability to remember the events leading up to Sean’s death.
This was because of the amount of time that passed between 21 August 2008 and two interviews conducted by the Independent Police Complaints Commission (IPCC) on 20 and 26 March 2009.
Therefore, the defence argued, White was not lying when he said he checked on Sean in the van.
When shown CCTV footage of himself, White was asked if he could remember the actions the courtroom saw him taking.
“I can work out from what I’ve seen on CCTV and what I’ve read,” he replied.
White was collected from Southwark Crown Court by a police van.
The case is the first instance of a Victims Right of Review being used to overturn a Crown Prosecution Service Decision to not prosecute a police officer, pointed out the Rigg family solicitor Daniel Machover.
He went on to describe how "the process had already been severely flawed by the seven month delay in interviewing Sergeant Paul White, and the further lapse of three years before Sgt White gave evidence at his trial.
"He then successfully argued that his memory of the event was compromised by the delay. The failure in this respect lies squarely at the door of the IPCC."
Sean’s sister Marcia Rigg said, “I am devastated. The jury’s verdict was a surprise to me and my family, but I will continue to fight for full accountability for those officers who were on duty at Brixton Police Station.
"That a custody sergeant can give false evidence in connection with a death in custody, something he accepts he did, is a shocking state of affairs. I await the MPS decision on disciplinary charges on this issue."