Jailed former police commander Ali Dizaei plans to sue prison authorities for failing to protect him from a fellow inmate.
The sacked Scotland Yard officer claimed not enough was done to protect him after a spate of racist and violent abuse more than two months ago.
The 47-year-old Iranian alleged the prisoner behind the threats physically attacked him six days ago at HMP Prescoed in Monmouthshire, South Wales.
Gwent Police launched an investigation after both men claimed they were assaulted by each other in a heated row.
Dizaei has been transferred to another open prison, believed to be Leyhill in south Gloucestershire, for his own safety.
But it was claimed his possessions, including clothes and photographs of his wife and children, were smeared in excrement before he arrived.
Dizaei has endured a torrid time since he was sentenced to four years' imprisonment for corruption in February.
He began his sentence in Wandsworth but was moved to Edmunds Hill prison in Suffolk where he was knocked out and had excrement poured over his head.
The former officer was then transferred to category D open prison Prescoed in Monmouthshire, which specialises in housing sex offenders.
Dizaei was convicted of attempting to frame an Iraqi businessman when they fell out over money after a trial in which he was accused of acting like a gangster.
The officer threatened, assaulted, falsely arrested and faked evidence against the younger man, who built him a vanity website.
The two men clashed in the street after being caught on CCTV arguing at a Persian restaurant, Yas, in west London.
Dizaei's legal team plan to launch a last-ditch bid to have his conviction overturned as he asks a panel of judges to reconsider his appeal.
The officer believes he has grounds to prove his trial was unfair and that his jail term is too harsh.
A spokesman for Ralli Solicitors, who represent Dizaei, said an inquiry was launched into racist threats against him in June.
He said: "Ali Dizaei made a complaint to the Prison Service on June 5 of racial abuse and threats of violence by a prisoner at HMP Prescoed.
"The matter was investigated and the prison found that '...it is highly probable that (the comments) contained a specific racist element...'
"The investigation also concluded that '...it is inconceivable, on the evidence available, that you (Dizaei) were the perpetrator in this case...'
"Dizaei maintains he was assaulted on Sunday August 1. Dizaei was taken to hospital and treated for his injuries.
"He maintains that family photographs have been defaced and threats have also been made against his wife and children.
"He has made a further formal complaint which is currently under investigation."
A Prison Service spokesman confirmed police were called in by governor Steve Cross after a confrontation last Sunday.
She said: "Two prisoners at HMP Prescoed claim they were the victim of an assault by the other on August 1. Neither prisoner required treatment in hospital.
"Due to the nature of the ongoing police investigation, one prisoner has been transferred to another prison."
The Metropolitan Police rejected an application under the Freedom of Information Act today asking for the total cost of several inquiries into his conduct.
An official said the information is held, but it would be too expensive and time-consuming to retrieve and compile it all.