Stephen Boyle, Austen House, Cambridge Road, Kilburn Park in London is accused of murdering Paul Boyle, 19, at Early’s Bar, Leabgarrow, Arranmore on October 3, 2009.
Mr Boyle has pleaded not guilty to murder but guilty of manslaughter.
Opening the trial Mr Paul O’ Higgins SC prosecuting told the jury the accused had admitted killing Paul Boyle but what they had to decide was whether this amounted to murder or a lesser crime of manslaughter.
Mr O’ Higgins said Paul Boyle who was from Arranmore was out on the night of October 2, 2009 with his father and friends.
The court heard Stephen Boyle left for London in 1988 and came back and forward to a house he built on Arranmore.
He told the court while the group was in one pub the accused Stephen Boyle was talking to Paul Boyle.
Mr O’ Higgins told the court the pair “didn’t get on well” and there was a row about money.
He said Paul Boyle who worked for Stephen Boyle in London was of the view that he was owed £400 sterling.
Mr O’ Higgins said Paul Boyle and his group moved to Earley’s Bar and Stephen Boyle arrived there later.
He said Stephen Boyle came up with a Heineken glass and “stabbed it into Paul Boyle’s neck”.
The court was told there were two major wounds and two minor wounds in his neck.
It was also told Paul Boyle was brought to the mainland to Letterkenny Hospital but he died at 10.20am on October 3.
Mr O’ Higgins said Arranmore has a population of 522 people and this killing caused “immense shock and sadness on the island”.
The trial continues before a jury of six men and six women presided over by Mr Justice Patrick McCarthy.