A man whose identity was revealed to lawyers defending a murder suspect has been awarded £134,000 compensation.
Ken Ralphs believes the police let him and his family down
Ken Ralphs gave Greater Manchester Police the mobile phone number of a gangland murder suspect on condition he received anonymity.
But his details were passed to the suspect killer's lawyers before the trial and he received death threats.
Mr Ralphs and his partner had to be given new identities and move hundreds of miles from their home in Stockport.
The Greater Manchester Police Authority has said that such a mistake must never be allowed to happen again.
Chairman, Councillor Stephen Murphy, said: "People who come forward with any information which might help a police inquiry should expect their identity to be protected wherever this is appropriate - and particularly in a case like this one.
"Quite simply, this should not happen. The police should never make mistakes like this.
"We must find out the full circumstances of this case and ensure this does not happen again."
Mr Ralphs' ordeal began after he responded to a public police appeal for help in a murder investigation, but police passed a file containing his confidential information to a suspect's solicitors.
The suspect's associates sent him death threats written in blood.
The former community leader and vice chair of Hazel Grove Labour Party in Stockport had his home attacked, CS gas sprayed in his face, a knife held to his throat and his fast food business petrol bombed.
Mr Ralphs and his partner had to be placed on a witness protection scheme and his foster son has moved abroad with other family members also relocating.
He said: "I was given a 100% assurance that my name and information would not be disclosed, this blunder has completely ruined our lives.
"It was an unprofessional way to act and the consequences of passing on my details that reached the criminal fraternity have been devastating."
He called for a public inquiry and the resignation of the chief constable of Greater Manchester Police
"If citizens cannot rely on the police to protect their anonymity when they are responding to a call for information then the public simply will stop helping the police to fight crime," said Mr Ralphs.
"No amount of compensation can ever pay for the scar that the police blunder has left on our lives."
He added: "You look out your window and wonder who it is every five minutes.
"We were in total fear after the police betrayed us. The witness protection scheme is a scam"
His solicitor Iftikhar Manzoor said: "Both my clients' lives are completely shattered. They still live in fear on a daily basis."
Mr Ralphs and his partner claimed negligence, breach of confidentiality and breach of human rights.
In an out-of-court settlement, Greater Manchester Police have agreed to pay compensation in what is believed to be the first case of its kind.
The force said it would be "inappropriate" to discuss the details.