Jurors in the trial by jury of a man accused of killing his cousin after he overdosed on heroin that he had given him are expected to retire to deliberate today.

John Mifsud stands charged and is pleading not guilty to the involuntary homicide of 32-year-old, David Spiteri in September 2005 and trafficking in heroin.

In yesterday's sitting, defence lawyer Malcolm Mifsud told jurors that his client had admitted to giving the drugs to his cousin in a police statement because he wanted to protect others, including an alleged supplier.

Dr Mifsud said that even though his client had admitted in the statement, he was confused at the time and had made a mistake.

The victim had died due to a mix of a tranquiliser and the heroin, which when taken together enhances the effect of the heroin by five times.

The Head of the Prosecution Unit at the Attorney General's Office held that the accused had known all along about his cousin's use of the pills but decided to go ahead and give the drugs to him anyway.

He added that the victim was a heavy drinker and was a habitual smack user together with the prescribed pills.

The prosecution rebutted these arguments and ask how one could say that the victim did not die because of the actions of the accused.

It that Mr Mifsud bought the drugs and then gave them to his cousin who then later died.

In the police statement he was clear and precise and the alleged supplier did not know that the drugs were meant for someone who took Valium 5, but his cousin did.

Were it not for Mr Mifsud's actions then his cousin would not have died.

Dr Barbara concluded his arguments by asking: if you knew that the person could not take a lot of drugs because he was taking pills do you go and give it to him anyway?

The jurors are expected to deliberate today.