The trial heard that Ms Greene, who was working as a prostitute, was last seen alive on the evening of February 13, 2011 and her body was found in a bog near Ballykeeran outside Athlone nine days later.
The jury heard memos of garda interviews with the accused on February 21, 2015 where he told them he had lost control and stabbed Ms Greene.
He told gardaí in an interview that he had given Ms Greene up to €40,000 and €20,000 in the previous six months.
Mr Devaney said he hadn’t paid any of the money back and he was waiting for a windfall to clear his debts.
He said he drove out to a bog on the Mullingar Road to talk to her but denied bringing a knife with him on the night in question.
Mr Devaney said Ms Greene threatened that she was going to tell her brother to collect her who would sort the accused out and and that she was swinging the knife at him.
In the interview he said he grabbed Ms Greene and wrestled with her before throwing her into a drain.
He told gardaí that she started running at him with a knife and he grabbed it from her and he pulled her to the ground before stabbing her. He said he later buried her.
When asked how many times he had stabbed her he said, “I just lost it completely. She was after doing so much damage, she was holding me over a barrel for years.”
He said he had met Ms Greene 10 or 12 years earlier when he was donating clothes to her neighbour.
He said Ms Greene propositioned him and they developed a relationship in which he would receive sexual favours in exchange for money. Mr Devaney said he would usually give her €20.
“It was opportunistic for me, she was available. A quick fix,” he told gardaí.
The accused’s brother-in-law Peter Boardman told the court via videolink from the UK that he brought a number of knives to Ireland he had used in his trade as a butcher.
He told Alex Owens SC prosecuting he was going to give them to a local butcher and left them at Mr Devaney’s house.
Mr Boardman testified he was shown a green-handled knife by Detective Sergeant Eamon Curley and said he recognised it. He said it was a five-inch boning knife.