A violent thug with convictions for weapons possession and affray was mistakenly released from Maghaberry Prison last week. Bungling jail bosses allowed Anthony Notarantonio out on two-day temporary release because they wrongly believed his sentence was coming to an end.

And the errors did not stop there — Sunday Life has learned that staff at Maghaberry were preparing to permanently release the 51-year-old, who has more than a year left to serve, at the end of the month.

Red-faced prison chiefs only realised their gaffe when they were contacted by this newspaper.

Notarantonio was sentenced to two years behind bars last November after pleading guilty to involvement in the February 2006 brawl that led to the knife killing of Gerard Devlin.

At the time of the fatal stabbing the bully was out on license for weapons possession.

A judge ordered that Notarantonio be returned to jail until October 23 to serve the remainder of his firearms conviction BEFORE starting a two-year sentence for affray.

This means the career criminal is not scheduled for release until October 2010 — not July 2009 like blundering prison chiefs believed.

The father of Gerard Devlin last night called for a Government inquiry into what he described as a “major mistake” by the Prison Service.

Pat Devlin also revealed that cops telephoned him on Wednesday to let him know that Notarantonio was being permanently released.

He said: “I'm calling for an inquiry into this. This is a major mistake and I want to know who was responsible for making it.

“The judge clearly said that Anthony Notarantonio wasn’t to start his sentence for affray until October 23 after serving the remainder or his firearms sentence.

“Why then did the Prison Service and PSNI think he was due out at the end of the month? It beggars belief and heads should roll.”

A Prison Service spokesman said: “We are seeking further clarification and legal advice in this case and cannot comment further at this stage.”

Last week we revealed how murder victim Gerard Devlin had once been friends with Arthur Notarantonio — the uncle of his eventual killer Francisco Notarantonio. They had been close pals but fell out in the 1990s, according to locals.