A prisoner was tonight being questioned about the killing of a drug dealer in Dublin’s Mountjoy Prison.
Gary Douch was stabbed to death, despite being placed on protection.
Gardaí confirmed a man, who is in his 20s, was arrested at the jail and was being detained at Mountjoy Garda Station for questioning over the death of the 21-year-old, who was serving three years for drugs offences.
A senior civil servant at the Department of Justice is to investigate the killing of Mr Douch from Dublin’s Tallaght.
It has emerged the drug dealer had last night asked staff to be taken off the main prison floor after being threatened.
He was put into a basement cell below B Wing with up to seven other men for his own safety. Hours later he was dead.
Both the gardaí and the Prison Service have launched separate investigations into the attack.
The Department of Justice has asked Michael Mellet, who currently sits on the Independent Monitoring Commission assessing paramilitary activity, to head up a further probe.
Minister for Justice Michael McDowell said the investigation would identify any failings which may have led to the death.
“The death of Mr Douch while in the care of the Prison Service is a tragedy for his family and is greatly regretted by me,” the minister said.
“A full Garda investigation is under way, but the further enquiries by a former senior public servant should help identify any system failure which may have occurred.”
Mr Douch was found with severe injuries in the basement cell at around 6.30am as prison officers did their morning rounds, according to a spokesman for the Prison Service.
He said officers immediately administered first aid and the young man was taken to the nearby Mater Hospital where he was pronounced dead just after 7.30am.
The scene of the attack has been preserved for garda crimescene investigators to carry out a forensic examination and a postmortem is expected to be carried out later today.
It is the second serious attack on an inmate in Mountjoy in less than a week. Nigerian man Goodwill Udechukwu, who was given a life sentence last Thursday for killing his wife, was seriously injured after he was stabbed three times after being attacked by a gang of up to 10 men.
He bludgeoned his Jamaican-born wife Natasha Gray to death with a lump hammer in their Dublin home in February 2003. He was in jail less than 24 hours before being set upon.
Conditions in Mountjoy have been severely criticised in the last few years. The most damning came from Inspector of Prisons Mr Justice Dermot Kinlen who described it as unacceptable and called for it to be demolished as far back as 2003.
Mountjoy is due to be moved to a new site at Thornton Hall in rural north county Dublin.
The Department of Justice said the inquiry will examine what action was taken by the Prison Service to safeguard Mr Douch and to clarify whether he expressed special concerns about his safety.
It will also establish what procedures were followed and their adequacy, procedures used to allocate prisoners to the cell in which Mr Douch died and the level of monitoring.
Mr Mellet will also have the power to issue recommendations. He has served as a member of the Council of Europe Committee for the Prevention of Torture and Inhuman or Degrading Treatment or Punishment and is a former Deputy Secretary in the Department of Justice.