Inside Graham Dwyer's cosy coffee mornings behind bars with killer Mark Nash
Dwyer, who brutally knifed Dublin woman Elaine O'Hara to death in 2012, spends his mornings plotting his upcoming appeal with Nash, who is also appealing against his conviction for murdering Sylvia Sheils (59) and Mary Callanan (61) in 1997.
Prison sources have confirmed to the Herald that the duo, who are both serving life sentences, are extremely close and that Dwyer has no other friends behind bars except for the 44-year-old Englishman.
"Nash is Dwyer's best and only pal - no one else has any time for him," one source said.
"They love drinking coffee and chatting in Dwyer's cell."
The two killers have forged a close relationship in the last six months and speak almost every day.
"They speak mostly about their appeals and both men are arrogant enough to think that they can get their convictions overturned," the source said.
"Dwyer sees himself as highly intelligent and superior and this doesn't go down well with his fellow lags."
Dwyer's attitude to his fellow prisoners has infuriated them and left him isolated, the source added.
"Most of the other prisoners see him as a devious pr*ck and they want nothing to do with him. He still plays poker in the recreation area of E3 but with a very small crowd."
Dwyer, who has grown a ponytail since being jailed, is also telling anyone who will listen that he will get his conviction overturned, because there is no physical evidence linking him to the brutal murder.
"Dwyer is very confident that he is going to get off," the source added. "He thinks he will be out by the end of the year because he says there is no physical evidence linking him to Elaine's horrific murder."
Dwyer has spent the last six months poring over boxes of evidence he has had delivered to his cell.
After he spends his morning drinking coffee with Nash, he reads the documents in great detail - he receives as many as eight boxes per week.
The perverted killer, who has a sexual obsession with stabbing and blood, doesn't mix with the other prisoners, preferring to keep himself to himself, unless socialising with Nash or playing poker.
Sources said Nash sees Dwyer as an intelligent man who may be able to help him in his own bid to have two murder convictions overturned.
"Nash sees Dwyer as someone who can help him with his appeal but he also seems to really like his company. But other prisoners say he is just using Dwyer to help himself," one source said.
The Midlands Prison, where most of Ireland's murderers and rapists are detained, has an inmate population of more than 870.
Dwyer was convicted of murdering Elaine O'Hara (36) on August 22, 2012, despite the childcare worker's remains not being found in the Dublin Mountains until September 13, 2013.
A jury found he stabbed O'Hara to death for his own sexual pleasure after sending texts to her for months about murdering her or someone else.
Dwyer's trial in March 2015 was one of the most high-profile in Irish judicial history.
His appeal was expected to be heard early this year but it has since been delayed until later in 2017.
The Herald reported last December that the Cork-born architect had assured fellow inmates that he would not be behind bars for Christmas 2017.
He even joked to one inmate that he has already picked out the restaurant where he would celebrate his release.
Dwyer is now devoting up to six hours a day to studying the grounds for his appeal.
His family continues to visit him regularly and Dwyer has maintained a letter-writing campaign to those friends and former colleagues who have not severed links with him.
However, his confidence over his appeal and his high profile have irked other prisoners.
Dwyer, who is referred to as Prisoner 88335, has clashed with several inmates in the Midlands Prison.
In 2015 he was injured when a rapist threw a chair at him in a row over a poker game.
Dwyer (42) received injuries to his arm as he tried to protect himself.
The attack was carried out by Salman Dar (34), who is serving a sentence for raping five women.
In a separate incident, Dwyer was punched in the face by another rapist, Noel Maher.
Sources revealed how Dwyer became "furious" when he heard that Maher (44) was spreading rumours about him.
Dwyer confronted Maher on Good Friday in a rage and pushed him.
However Maher - who is behind bars for sexual assaulting and raping his stepdaughter - punched the killer, sending him crashing to the ground in pain.