A Metropolitan Police officer facing a possible gross misconduct hearing following the death in custody of a mentally ill man has been suspended.
Sgt Paul White was the custody officer when Sean Rigg died at Brixton police station in south London in 2008.
The BBC understands Sgt White had requested to retire, which would have meant he avoided a misconduct hearing.
Campaigners said it is only because of pressure from the Rigg family that Sgt White's retirement was rejected.
It is understood the Independent Office for Police Conduct (IOPC) told the Met that Sgt White and another officer should face a misconduct hearing.
Regulations were changed in December, meaning a police officer can now be pursued for gross misconduct even if they retire or resign.
However, the changes would not have applied to this case because of its age, the IOPC said.
Under those rules the only the way the Met could prevent an officer who is subject to a misconduct investigation from retiring is by suspending them.
A Met spokesman confirmed "a sergeant investigated by the IOPC in connection with the death of Sean Rigg" has been suspended and had his request to retire "rescinded".
Until Friday Sgt White had been a serving officer "on restricted duties", he added.
Deborah Coles, director of criminal justice charity Inquest, said Sgt White would have avoided disciplinary action if not for the pressure put on police by the Rigg family.
"Bereaved families should not have to do the job of the Metropolitan Police and IOPC and fight to ensure there is accountability," she added.
"Yet again the police complaints process has been brought into disrepute. Police officers are public servants and cannot be above the law."
Mr Rigg's sister Marcia said she was "appalled" the officer might have avoided a hearing.
She was preparing to ask the IOPC to go to the High Court if Sgt White's retirement had been approved.
In 2012, an inquest jury found police had used unsuitable force when they arrested Mr Rigg, a 40-year-old musician who was a paranoid schizophrenic.
He was handcuffed, forcefully restrained face down and confined in a police van.
Mr Rigg collapsed after arriving at the station, where he had been put in a holding area, and died from a heart attack.
He would have had his 50th birthday on 11 February.
Last year, the Crown Prosecution Service decided none of the police officers should be prosecuted over his death.
Sgt White stood trial for perjury in 2016 and was acquitted.