A lag "failed a drugs test" after allegedly launching an attack in which he elbowed and spat at a prison officer - days after being involved in a football match in Croke Park, the Irish Mirror can reveal.
And we have learned that the prisoner was wearing his match gear when the incident occurred in Dublin's Mountjoy prison at around 2.30pm on Friday last week.
A football game took place between a side of inmates from Mountjoy and another team at Croke Park last week.
The inmate who carried out the alleged attack was involved in the event.
Sources revealed that following the incident yesterday, he was tested for drugs and failed it.
And now a major line of inquiry in the investigation is whether drugs were left for him in and around Croke Park and may have successfully been smuggled back into the prison.
A source said: "It's another shocking incident in which a prison officer was targeted whilst doing his job.
"At some stage after that game, he consumed drugs and this is what has happened."
The prisoner was last week moved out of the landing he was on and segregated from others.
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The Irish Mirror has learned he is set to lose his status as an enhanced prisoner in the disciplinary process.
One of those perks was being allowed out from the Mountjoy property to play the GAA game this week, in which sources said around 200 people were invited to watch on.
Retired Dublin inter-county football star Philly McMahon has helped out with prisoners in Mountjoy for some years.
He and comedian Rory O'Connor of Rory's Stories had been training inmates for a game against prison officers before Christmas.
