Officers will be cleared of any wrong-doing after a dissident republican prisoner’s suicide in custody, a leading Police Federation figure predicted last night.

Terry Spence was speaking after John Brady was found dead in his cell at Strand Road station in Londonderry on Saturday evening.

Brady had been arrested in the city on Friday and held overnight in relation to an alleged assault in a domestic incident.

A website that had been campaigning for the 40-year-old notorious murderer last night called his death “mysterious”.

Republican splinter group Eirigi called for an independent inquiry “given the history of RUC and PSNI holding centres in the north”.

But Mr Spence, Northern Ireland Police Federation chairman, told the Belfast Telegraph he was confident officers would be cleared of any wrongdoing.

“At this early stage it looks like there was nothing at all to suggest the police were responsible for his death,” Mr Spence said. “The police had no bearing on what happened whatsoever.

“I’m quite sure there will be a thorough investigation and the police will be exonerated from any responsibility.”

Northern Ireland's Police Ombudsman Al Hutchinson yesterday launched an investigation into Mr Brady’s death.

A post mortem, due to be carried out today, is expected to determine how the Strabane man died. The ‘Free John Brady Campaign’ website — which calls for the release of all ‘political hostages’ — said his death was “mysterious”.

“Serious questions have been raised due to the fact that John had a consultation with his solicitor and was in good spirits less than one hour before he was reported dead,” it said. “The police have said he was found in a ‘room’. We will endeavour to keep you posted.”

MP for West Tyrone Pat Doherty said the death of the convicted killer needed to be thoroughly examined.

Sinn Fein MLA and Policing Board member Martina Anderson said the “very fact he died in daylight hours needs to be taken into account”.

Mr Hutchinson said the Ombudsman’s office would conduct “a fair, independent and impartial investigation”.

“We will be interviewing all officers and other witnesses who may have been in contact with Mr Brady in the time leading to his death,” Mr Hutchinson said.

“Once we are in possession of all of the facts we will be able to inform the family and the wider public about how this tragic death happened.”

Eirigi spokesman Brendan McKenna offered condolences to the Brady family.

“Given the history of RUC and PSNI holding centres in the north, we will be calling for an enquiry independent of both the PSNI and the British state into this incident,” Mr McKenna added.

It is understood Mr Brady was on short term prison leave as part of a programme aimed at preparing prisoners for release when he was arrested at the weekend.

Last year, an attempted murder charge against him was was dropped over concerns about DNA evidence.

He had been charged with leaving a bomb under the car of a former RIR soldier in 2002, but the case was reviewed and dropped after a judge criticised low copy number DNA evidence during the Omagh bomb trial.

Mr Brady had been jailed for the |murder of a police officer in 1989.

In 1991, he pleaded guilty to killing RUC Reserve Constable David Black, who died after an under-car booby-trap device exploded near his home on the outskirts of Strabane.

He was initially released on licence in 1998 after the Good Friday Agreement, but his licence was later revoked and he was returned to prison in November 2003.

History of self-harm in jails

John Brady is not the first person to die in custody in Northern Ireland in recent times.

His suicide comes days after four prison service medics were suspended from duty after an investigation into the suicide of an inmate inside the high security Maghaberry jail in Co Antrim.

The staff work in the prison’s medical centre, where convicted sex offender John Anthony Deery was found hanged in August. The 50-year-old died the next day in Belfast’s Royal Victoria Hospital. He was the second Maghaberry inmate to kill himself in little over 12 months.

The action against the four healthcare workers comes after a probe into the circumstances of the death by the region’s Prisoner Ombudsman.

While the latest suicide occurred in police custody, and not on the Prison Service’s watch, the death is sure to prompt fresh questions for the authorities on practices for monitoring individuals being held in cells.

Meanwhile, Colin Martin Bell (34) was found dead in his cell at Maghaberry prison in August 2008.

The father-of-two was in a ‘suicide watch’ cell because he had a history of self-harming.

Bell was serving a life sentence for the murder of Michael O’Hare in a flat in Bangor, Co Down, in 2003.