An Irishman stabbed a fellow countryman in the neck during an alcohol and drug-fuelled party, a court in Australia has heard.
Vincent Crowe (34) attacked Kenny Meyler (21) - who he did not know - during a party in Scarborough in Perth in February last year.
Victim Kenny Meyler died a week later from his injury.
Crowe has admitted killing Mr Meyler - but denies murder.
Neither man had met each other before the incident which occurred on February 9.
Both were drinking with mutual friends.
The jury was told that the group ended up at a party in Scarborough where Crowe continued drinking and took mephadrone, a drug commonly known as 'meow-meow'.
The party, the prosecution said, continued until 2.30pm the following day, February 10.
At this time, Crowe took a knife and "walked to where Kenny was sitting and thrust it with force into the right side of Kenny's neck".
An hour beforehand, a friend of Crowe's was involved in an altercation with the victim.
Witness Michael Lonergan, who was at the party, told the court the atmosphere beforehand was "good".
In her address to the jury, defence counsel Judith Fordham said Crowe accepted his actions caused the death of Mr Meyler.
She described Crowe as an alcoholic with previous drug abuse problems - however, she said he had not taken drugs for some time before the party.
The trial is expected to last two weeks.