A cop dressed up as a clown to mock a female prisoner in front of a laughing colleague.
Watchdogs have told Police Scotland to re-investigate how they handled complaints following the flashpoint.
The force have already admitted the incident was “humiliating and degrading” in an internal misconduct probe.
But Police Scotland failed to investigate the allegations properly, the Police Investigatory and Review Commissioner (PIRC) Michelle Macleod has found in the new report.
The incident was included within 14 complaints the unnamed woman made after she was arrested at her flat following a disturbance.
It occurred after the prisoner called the female officer “a clown” when she was stripped and refused stomach ulcer medication.
The police security and custody officer – referred to as PSCO J in the report – went back into the cell wearing a mop on her head and pink lipstick on her mouth and cheeks and said “Do I look like a f***ing clown now.”
PIRC’s report found Police Scotland failed to properly deal with nine of the allegations and has made 10 recommendations. It added: “The applicant said that she was shocked and ‘felt degraded because she was sitting on a mattress covering herself up’.”
The incident happened in front of a female police constable who was “smiling and laughing”, according to paperwork.
The officers told an original investigation that dressing up as a clown had been an effort to “defuse the situation and hopefully make the complainant laugh”.
Police Scotland said the behaviour was unacceptable and recommended PSCO J be disciplined. She has since died.
But PIRC found that did not go far enough and police should have recorded the complaint as “oppressive conduct/harassment” instead of “incivility”.
The watchdog also said the constable who laughed should have been probed for failing to tackle her colleague’s behaviour.
PIRC also found claims that the woman was denied a solicitor were not thoroughly investigated after PSCO J allegedly told her: “Clowns do not phone solicitors.”
Police Scotland also failed to properly investigate claims the prisoner, who later pled guilty to threatening behaviour and assaulting an officer, was denied water and was taunted by PSCO J who drank out of a bottle in front of her.
The force had also earlier apologised after a male PCSO put two fingers up at the prisoner. He has since retired.
Scottish Labour justice spokesperson Neil Bibby said: “No one should abuse their position of trust and incidents like this must be properly investigated. “
Last year, a damning report by Dame Elish Angiolini found major issues over how Police Scotland handle complaints.
Scottish Tory justice spokesman Liam Kerr said: “The details of this case are appalling as are the police’s subsequent failure to investigate them properly.
“Four months ago, former Lord Advocate Dame Elish Angiolini produced a report which laid bare a litany of serious problems with Scotland’s police complaints system.
“Cases like these remind us of the fundamental importance of maintaining trust in policing and building a fair and transparent complaints system – for the benefit of the public and officers.”
A Police Scotland spokesperson said: “In June 2019 we wrote to the individual concerned to apologise for a number of failings in relation to their detention.
“Where inappropriate conduct is brought to our attention it will be considered by Professional Standards.
“We will work with the PIRC and the complainer to address any further concerns.
“In addition, Police Scotland is in the process of establishing a new model to improve how we deal with complaints from members of the public.”
