Gardaí and Irish Prison Service are investigating the origins of a bag of heroin which killed a prisoner in Mountjoy Prison who had swallowed it in an attempt to hide it from prison officers.

The dead man, named as Pascal Doyle, a 30-year-old father of two with an address at Staplestown Rd, Carlow, was a convicted drug dealer.

He was found unconscious in his cell in Mountjoy, but despite efforts to save him he was pronounced dead within an hour. He was taken to the Mater Hospital where he was pronounced dead at around 4.15am.

Doyle had served a number of prison terms and was in the middle of a short sentence for mainly road traffic offences.

Known for selling drugs in Carlow, he had over 60 previous convictions including for drug dealing, stealing cars and other thefts, threatening gardai and public order offences.

He had been in custody since June 8th and two investigations into his death this weekend by the Garda and prison authorities are trying to establish if during any outside visits for court appearances he was passed the drugs that killed him.

Doyle had swallowed a bag of heroin which became lodged in his stomach and burst, leaking into his body and killing him by way of overdose.

While he had been involved in an altercation at the prison last week, he had not sustained any serious injuries and any link between his death and that incident has been ruled out.

The postmortem results did not detail how the drugs had been wrapped, though prisoners often package drugs for swallowing inside several condoms, one over the another, or inside small bags fashioned from rubber gloves.

He was found at around 3.30am yesterday unresponsive in his cell by staff operating routine checks on prisoners in cells through the night.

Doyle was still alive when found and prison officers and medics worked on him before he was taken to the Mater Hospital opposite the prison on the North Circular Road. However, he was pronounced dead at the hospital at around 4.15am.

While drug-taking has been rife throughout most of the prison system for decades, efforts by the prison authorities in recent years to restrict the flow of drugs into jails have been successful, making contraband much harder to smuggle in.

Prisoners have long swallowed parcels of drugs as a means of concealing them; selling them or consuming them after they have passed through their system.

While the practice is not uncommon, deaths from this practice are rare.

In 2009 the dangers of prisoners carrying drugs internally or “body packing” were highlighted at an inquest into the death of a man who died of heroin and sedative drug toxicity in custody.

Mark Turner Kelly (24), Dunsink Avenue, Finglas, Dublin, was found unresponsive in a padded cell at Mountjoy Prison on August 29th, 2009.

Dublin City Coroner’s Court was told in 2010 that three packets were found on the floor of his cell, one of which contained heroin and two sedative drugs.

A further packet was removed from his rectum at the Mater hospital. He had passed other drugs just before his death that he had concealed internally by swallowing.