Evil Joe, who has now spent 14 years behind bars for the horrific murder of innocent wife Rachel in 2004, is understood to have submitted the application last month which, if approved, could have seen him enjoying up to three days of freedom this Christmas.
It's understood that in making the request, the 45-year-old said he hoped to spend the holidays in the company of his and murdered wife Rachel's two sons.
However, the Sunday World understands that authorities rejected the application after considering all factors associated with his case.
It's believed these factors are likely to have included the high-profile nature of his crime, publicity which would have accompanied his potential release, and the impact of such a release on the family of his victim.
A spokesperson for the Irish Prison Service yesterday declined to comment on queries from this newspaper stating: "The Irish Prison Service does not comment on individual prisoners."
Rachel's dad Jim Callaly yesterday told the Sunday World he believes the Irish Prison Service have made the right decision in blocking O'Reilly's efforts to get out for Christmas.
"He never admitted to killing Rachel so there has been no remorse," he told this newspaper.
"And I think that is one of the criteria that has to be considered in an application like this.
"I don't think he should ever be let out of prison. He's a dangerous psychopath.
"He gets his kicks out of seeing people suffering.
"The morning he murdered Rachel he set my wife Rose up to find her.
"He knew what Rose would find when she entered the house that day and he got a kick out of that or he wouldn't have done it that way.
"Then after he picked up the boys from school, he drove back to the house and was walking in with them knowing that Rachel lay dead inside in a pool of blood and they would see that.
"There's no point in saying he didn't know that because he murdered her. Thankfully Rose saw them coming in and she stopped that from happening.
"And when he re-enacted Rachel's murder in front of me and Rose, he enjoyed it. That's the kind of dangerous psychopath he is.
"He'd be a very dangerous fella for the Prison Service to be considering letting out. There is nothing to stop him doing something like this again because he has never shown remorse.
"So, no I don't think he should ever get out. It would have caused huge upset to us if they approved this."
O'Reilly is currently serving his life sentence in Wheatfield Prison.
The 6 ft 5-inch brute bludgeoned Rachel to death with a dumbbell at their Naul home, in Dublin on October 4, 2004, and staged it as a burglary.
He engaged in a nine-month affair with advertising executive Nikki Pelley, 42, before he killed his wife.
He then appeared on The Late Late Show with Rachel's mother, Rose, to appeal for witnesses.
Two weeks ago, the murder featured on RTE on the true crime series 'The Case I Can't Forget.'
The documentary recounted how Rose had to sit next to her daughter's killer during their Late Late appearance, all the while suspecting O'Reilly had killed Rachel.
The documentary also recalled how O'Reilly 'scoffed' down a plate of sandwiches, crisps and tea in the green room before his Late Late appearance, and then spent the night with his lover, Nikki Pelley, after the show.
O'Reilly has two sons with Rachel, both of whom are now over 18 years of age. He previously tried to arrange one-on-one visits with the boys outside of prison with the meetings meant to take place in a neutral venue under the supervision of prison officers.
However, it's understood that such a request has not yet been granted.
During his trial in 2007 O'Reilly tried to claim he was at work when a burglar broke into the house and killed his wife.
But phone records showed he had travelled from work back to the secluded family home before returning to central Dublin.
It was the first high-profile case where mobile phone location played a crucial role in pinning-down a person's movements.
As O'Reilly drove from Dublin city to The Naul and back again his phone 'pinged' at a number of the masts it passed, including one at a quarry just down the road from the home he shared with Rachel and their two sons.
O'Reilly has now exhausted every appeal process open to him in trying to overturn the conviction.
He continues to apply for parole every two years.