A 24-hour drugs amnesty at Maghaberry jail in, Co Antrim, has failed, it emerged today.
Not one prisoner handed over secret stashes following the death of a man from a suspected overdose inside the complex.
The victim's cellmate, who was due to be released hours later, has been questioned by detectives.
At the same time, authorities gave the inmates a day to hand over hidden drugs. A Prison Service spokesman said today: "We are disappointed but not surprised."
Kevin Slevin (27) from Armagh, was found dead in his cell on Monday. He had been serving a sentence at the jail near Lisburn, Co Antrim, for possession of drugs with intent to supply.
Unconfirmed reports suggested he may have taken diazepam. His cellmate, who was also convicted for narcotics offences, was taken to hospital after the discovery.
He has since made a recovery and was arrested by police last night. Prison chiefs at Maghaberry, where three warders were injured last month during attempts to smuggle in a diazepam batch, denied drugs were rife.
"We have considerable success in stopping them getting in, but a truly determined smuggler will get them in," the spokesman said.
"We have preventative measures to stop drugs coming in such as passive drug dogs and frequent searches.
"There are also education programmes to highlight the dangers and treatment for prisoners who come in with problems.
"But the prison just reflects in the community."