Murder accused David Mahon's actions on the night his stepson was killed were "straight out of the 'how to get away with murder' handbook", a court has heard.
Closing arguments have detailed how Mr Mahon disposed of the knife used to stab Dean Fitzpatrick and failed to call 999 on May 26, 2013.
Mr Mahon (45) has denied killing his stepson, the brother of Amy Fitzpatrick, who went missing in Spain in 2008.
Mr Fitzpatrick (right), a father of one, was stabbed to death outside Mr Mahon's apartment at Burnell Square, Northern Cross in Malahide.
Prosecuting counsel Remy Farrell SC said that the stabbing took place in a split second, but the jury would have to look at the surrounding hours and minutes to see what was going on in Mr Mahon's mind.
Mr Farrell said that the reality was that Mr Mahon was drunk, angry and agitated and that he stabbed his stepson and then set about doing everything he could to try to "get away with murder".
He told the jury at the Central Criminal Court: "You might think it was crazy to throw away the knife, but that's what people do.
"It was straight out of the 'how to get away with murder' handbook - you get rid of the weapon and you don't ring 999."
Mr Farrell said there was no contest about a lot of the evidence and accused Mr Mahon of telling "lie after lie after lie".
There was no contest that Mr Mahon had the knife in his hand and it entered Dean Fitzpatrick's abdomen, killing him, he said.
The jury was told it must decide on Mr Mahon's intent: "Was it his intent to kill him, to cause him serious harm?"
Mr Farrell told the jury to "judge a man by his actions, judge a man by his words".
He said Mr Mahon spent the Saturday that Mr Fitzpatrick died "frenetically" trying to get in contact with him.
He said there were 12 mobile phone calls from Mr Mahon to Mr Fitzpatrick between 9.40pm and 10pm on that Saturday.
There were also six calls to Dean's former girlfriend, Sarah O'Rourke.
Mr Farrell said Mr Mahon had also sent Dean a text message earlier in the day threatening to stab him.
He told the jury that they also know about Mr Mahon's mood that night, with Ms O'Rourke telling the court he was "aggressive".
Mr Farrell said Ms O'Rourke's evidence was that Mr Mahon was looking for Dean, and while speaking to her he threatened he would "stick a knife in her neck".
Mr Farrell said the defence has not suggested that Ms O'Rourke made up this threat.
The jury was also told that after Dean was stabbed, Mr Mahon told his friend Karl O'Toole to get him out of the apartment.
The pair left in Mr O'Toole's taxi and they drove around north Dublin, stopping for a drink in the Balrothery Inn in Balbriggan, before they drove to the accused's father's home in Santry.
Mr Farrell said Mr O'Toole gave evidence that as they were leaving the M1 at Balbriggan, Mr Mahon said to him he thinks "Dean is dead" and he thinks "the knife went through him".
The jury heard that in the minutes after Mr Fitzpatrick's stabbing, Mr Mahon had given "a very good impersonation of a man who has just admitted murder".
It was only later, said Mr Farrell, that Mr Mahon "cooked up" a story to gardai that it had been a terrible and "wholly innocent accident".
If it was just an accident or suicide, why did Mr Mahon flee the scene and dispose of the murder weapon? asked Mr Farrell.
The jury heard that gardai asked Mr Mahon why he threw away the knife, and he told them "don't ask me, I don't know why".
Mr Farrell also questioned why Mr Mahon told Mr O'Toole to stay off the motorways to avoid CCTV cameras.
When he was interviewed by gardai, Mr Farrell said Mr Mahon told them the "farcical story" that Mr Fitzpatrick had "walked into the knife".
He said the evidence of the pathologist, Dr Michael Curtis, was that the knife entered Mr Fitzpatrick with moderate or considerable force.
He also said it was clear from the gardai memos that Mr Mahon did not know if it was an accident or suicide.
"Why did Dean Fitzpatrick run away if it was suicide? Why did David Mahon run away if it was suicide?" he asked.
Mr Farrell said Mr Mahon told gardai "lie after lie after lie" in the five interviews that they conducted with him.
Mr Mahon told gardai it wasn't his style to "run and hide" but that was exactly what he did by fleeing the scene, said Mr Farrell.
The jury heard that one of the biggest lies Mr Mahon told to gardai was that he didn't know how serious the injury was.
"When you stick a knife into meat, you know when you hit a bone," said Mr Farrell.
He said David Mahon knew the knife had gone right the way through, because he told Karl O'Toole, "Dean is dead".
He said Mr Mahon told gardai that it was only a graze, and there was only a small bit of blood on the knife, but this was to cover up the most shameful part of his actions.
"He knew Mr Fitzpatrick was terribly and possibly fatally injured and he ran and he did not care about Dean, he cared about himself."
Mr Farrell said that if Mr Mahon's defence is that of accident or suicide then he must be the "most unfortunate man in Ireland due to a confluence of remarkable events that put him in the wrong place at the wrong time".
Mr Farrell said David Mahon made a pretence at decency by going to the gardai the next morning, but the reality was that he "ran and did everything he could to avoid the authorities".
The case will continue on Tuesday before Ms Justice Margaret Heneghan and a jury of six men and six women.
Closing arguments from the defence will be put before the jury at the Central Criminal Court.