A dopey criminal caused a security alert at Mountjoy Prison when he spent almost six hours on the roof after collecting drugs that were thrown up on to security netting.
Sources said Dubliner Liam Deegan (25) "consumed the drugs" during the stand-off.
"He was in a highly intoxicated state. The drugs were taken," a source said last night.
Deegan, from Rathmore Drive, Tyrrelstown, is serving a three-and-a-half year sentence for "producing an article" and has been locked up since last year.
He has multiple previous convictions.
Deegan yesterday spent more than five-and-a-half hours on the roof before he eventually agreed to come down at around 7pm.
He is likely to be disciplined for the bizarre incident.
Mountjoy has in recent years erected an expensive system of netting around its walls in a bid to prevent dealers and associates from throwing drugs into the exercise yard.
Despite such measures, drugs do get into prisons, with dealers using ever inventive methods to bypass security measures.
Last June, dozens of prisoners were "left like zombies" after consuming narcotics from a drone that crash-landed in Wheatfield Prison in west Dublin.
The majority of drugs that were on the €2,000 drone - known as a quadcopter - made it into the jail after it came down in an exercise yard.
The drone got caught on anti-helicopter wires, put in place to prevent any airborne escape attempts using larger aircraft.
A number of prison staff noticed the commotion as the device crash-landed and tried to intercept the operation, but they were too late.