Fatal Sydney basher sent texts to victim

A man who fatally bashed his best friend sent a flurry of texts after the attack and told his mate's mother "I will cop anything that is coming to me".

Dennis O'Brien, 28, died a week after being bashed by Mathew Beattie in the granny flat of his Port Stephens home in June 2013.

Beattie has pleaded not guilty to murder.

The court has previously heard Beattie was drunk at the time of the attack and had taken speed and prescription medication.

While he admits killing his friend, he says he never intended to cause serious injury.

Speaking at his Supreme Court trial on Friday, Mr O'Brien's mother, Lisa Carr, said Beattie had sent text messages to her son's phone while he lay in hospital.

In the texts, Beattie said he had been "f***** up" and "just wanted Den (Dennis) to be ok".

"I message him because he's my mate, Lisa," Beattie told Ms Carr in a text sent to Mr O'Brien's phone.

"I will cop anything that is coming to me."

During the exchange of messages, which lasted a number of days, Ms Carr sent a photo of Mr O'Brien with the caption "this is what you did to my son".

Beattie, his wife and Ms Carr had all travelled from Campbelltown to visit Mr O'Brien.

Ms Carr, who was staying in the granny flat on the night of the attack, says she witnessed part of the assault.

She has previously told the court that her son did not fight back as he was punched and head-butted.

The jury has also heard Ms Carr, Mr O'Brien and other witnesses to the attack were initially hesitant to co-operate with police.

The day before he died, Mr O'Brien told his mother, "I don't remember what happened and I don't care".

Beattie turned himself into police following Mr O'Brien's death.

The trial continues.