A murder trial witness has called the accused a "scummy b*****d" and insisted he did not tell lies in his evidence to the jury.
The witness, who cannot be named by order of the court, insisted under cross-examination that the accused told him he had put the deceased "out of his misery" and that he had "slaughtered him".
He also said the accused is trying to claim insanity, which the witness described as "bulls**t".
In his direct evidence on Thursday, the witness said the accused man, Philip Dunbar (20), came to his home shortly after the stabbing and was carrying a bloody knife.
He said Mr Dunbar "boasted" about having stabbed 23-year-old Adam Muldoon, a homeless man with cerebral palsy, and said he had "put him out of his misery".
He also said he was at Sean Walsh Park in Tallaght the following morning when Mr Dunbar disposed of the knife that was allegedly used.
Mr Dunbar, through his barrister Giollaíosa Ó Lideadha SC, has accepted that he must have stabbed Mr Muldoon, but said he has no memory of it.
He has pleaded not guilty to the murder of Mr Muldoon at Butler Park, Jobstown Park, Tallaght, on June 22 or 23, 2018.
Mr Ó Lideadha cross- examined the witness at length yesterday, asking him why he did not say to gardaí in 2018 certain things that he had said in front of the jury.
The barrister said the witness did not tell gardaí that the accused told him he had put Mr Muldoon "out of his misery" or that he had "slaughtered him".
The witness responded that he did not know why it was not in his statement, but insisted that Mr Dunbar had used those words.
Mr Ó Lideadha referenced a part of the statement where the witness called the accused a "scummy b*****d". In the stand the accused said: "He is a scummy b*****d."
The barrister suggested the witness has a "passionate interest in attacking Philip Dunbar and saying the worst possible things that come into your head".
The witness said that was not true.
Mr Ó Lideadha also challenged the witness's testimony that the accused had to change hands during the stabbing so he could keep going.
He asked him if he had made this up after reading media reports stating that Mr Muldoon was stabbed more than 180 times.
The witness said he had no need to make anything up.
When asked if he had done his best to help gardaí, the witness said that at first he was worried people would call him a "rat", but later decided he did not care.
He said this was not "some gangland s***e" but was "scummy", and telling the truth was the right thing to do.
He said that when he spoke to gardaí a second time, he told them "nothing but the truth".
Mr Ó Lideadha also asked the witness if he was sure he did not go into the park where Mr Muldoon was stabbed.
"One million per cent sure," he responded, adding that CCTV would prove he was at home at the time.
The jury was told on Thursday that the accused "boasted" about stabbing Mr Muldoon.
The witness said the accused called to his house following the stabbing, still carrying a knife stained with the deceased's blood, and told him he had lured Adam 'Floater' Muldoon into a field, stabbed him and cut his throat.
He said the accused told him: "Now I know what it's like to be a killer. I know how it feels to be a killer."
The witness, who described himself as a drug dealer, told prosecution counsel Pauline Walley that he was at home on the night of June 22 going into the following morning when the accused sent him a message on Facebook saying he needed to tell him something.
At about 12.15am the accused called around. He was "a bit agitated", the witness said.
He said Mr Dunbar told him he had lured Mr Muldoon into a field, stabbed him and cut his throat.
The witness said Mr Dunbar told him he knew Mr Muldoon was dead "the second I got him in the neck", but he "kept going and kept going", changing the hand he was holding the knife in so that he could continue.
The cross-examination will continue on Monday in front of Mr Justice Paul McDermott and a jury of six men and six women.