A West Auckland man who attacked his unwell mother says he wasn't thinking when he picked up the hammer that killed her.
Martin Marinovich, 28, gave evidence in his own defence during his murder trial at the High Court in Auckland today.
He strangled his mother Noeleen before repeatedly striking her head with a hammer in their Oratia home last February.
Mr Marinovich accepts he killed the 59-year-old woman but says he didn't intend to end her life when he attacked her.
Today, he told the jury he was helping his mother to the toilet around 10pm that day when they began to argue over money.
The court has heard Mr Marinovich was his mother's primary caregiver when she died; responsible for running the house and looking after her.
She owned the house they lived in so the defendant covered food and bills with his mother's sickness benefit that provided $550 a week.
Mr Marinovich said money was "extremely tight" and his mother wanted to book a trip to Queenstown for her 60th birthday that year that was unaffordable.
"At some point during that argument I could only describe it as like a light switch turning on. I just got so angry. Not even anger; more like rage.
The next thing I can remember is having my hands around her neck like that [defendant stretches out his arms] and pushing her to the ground."
Mr Marinovich said he strangled her with both hands for ten to 15 minutes before covering her with a blue mink blanket on the sofa.
"When I did so blood poured out of her nose and that was the point when I believed she was dead. That caused me to enter a state of what I can only describe as total and complete panic at that point."
"I can remember picking up the hammer from the bookshelf, turning to mum, kneeling over her, holding the hammer in my left hand and striking her head multiple times."
Mr Marinovich was emotionless as he described dropping the hammer, pacing around the lounge and then sitting in the bathroom for what felt like a long time.
"I can remember that my left arm, my hands and my chest were covered in blood."
He told the jury he returned to the lounge to "check on" his mother before having a shower and driving to a nearby train station where he called police.
Mr Marinovich was very clear to specify his mother was dead after he strangled her and before he attacked her head with a hammer.
But the jury has heard from a forensic pathologist who said Ms Marinovich had bruises to her hand and forearm consistent with defensive injuries.
While the pathologist said it was possible she died of strangulation, it was his expert opinion her cause of death was the blunt force injuries to her heard.
Crown prosecutor Robin McCoubrey began his cross-examination by asking the defendant why he hit his mother with a hammer.
"I have no reasonable answer to that question. I can't understand my own actions at that point. I can't understand why I went looking for anything else.
"I don't know why I picked up the hammer. I just, I can't answer that question."
McCoubrey put to the young man that even people acting in rage, "the red mist descending", were acting deliberately and intentionally.
"I cannot remember any form of conciensce thought that I had. I did not make a decision essentially that I can recall," Mr Marinovich replied.
The defendant said he was under "significant stress" at the time of his mother's death and it had brought about immediate relief that he could stop lying about studying law.
The court has heard Ms Marinovich had bipolar disorder and became more prone to falls as she grew older; spending time in hospital a week before she died.
The defendant said he'd observed his mother having manic episodes, throwing items around the house, and bouts of paranoia from a young age.
He told the jury she had been "stable" since 2007 but became increasingly dependant on him as her physical health deteriorated in older age.
The 28-year-old said he'd lied to his family that he'd been studying law at Auckland University since 2010 when he had actually dropped out of an arts degree in first year.
"I didn't sit the exams at the end of the second semester that year and I left university after that. I think I chose the wrong degree. I didn't find it particularly interesting or challenging."
Instead, Mr Marinovich said he spent his days helping his mother around the house, cooking, cleaning and, in the last twelve months of her life, cleaning her after the toilet.
Both Crown and defence will make closing addresses tomorrow morning before Justice Walker sums up the case.