Today in the High Court at Auckland, Crown prosecutor Robin McCoubrey said the jury should reject the idea that the victim was dead before hammer blows rained down on her.
"Maybe just maybe, he can't accept that's how he killed his mother. In such a gruesome way.
"However sad, however horrible, however desperate this is - if you look at the evidence coolly and calmly as you have to, he killed his mother that night."
She was alive when he started to strike her with the hammer, McCoubrey said.
Nothing spoke louder than his actions that night, he said.
"The defendant is guilty of his mother's murder."
Police working at the scene after Noeleen Marinovich, 59, died in Oratia. Photo / Doug Sherring
Defence lawyer Shane Tait told the jury everyone agreed what unfolded was a tragedy.
"There is no way she deserved to die at the hands of her son."
But Tait said his client had been consistent with police ever since he made a 111 call at the Sturges Rd train station, admitting he attacked the 59-year-old but maintaining he did not intend to kill her.
And in his version of events he fatally strangled her after an argument about money, Tait said.
"There is a $4000 hole in the bathroom floor that needs to be fixed."
The pair depended on Noeleen Marinovich's benefit, which was about $549 a week, and she was hoping to visit Queenstown for her upcoming birthday.
There were other pressures too weighing on the defendant; his mother's worsening health meant she needed help in the bathroom and was unsteady on her feet.
The Oratia home they shared had become grubby while he took care of the shopping and other tasks, even including dying his mother's hair.
He had cared for his mother since he was 9 years old, the court heard.
Tait said as a result of all of this pressure at home he lost "all reasonable thought".
The defence case was that he strangled her to death and then paced around the house.
While she was lying deceased on the floor he then picked up the hammer and struck her multiples times. He does not remember how many.
Martin Marinovich's trial began in the High Court at Auckland on Monday. Photo / File
Tait said the blood spatter evidence supported that she was on the floor when she was struck multiple times with the hammer.
"It seems he doesn't know why he did that."
Although that might be indicative of his state of mind, he said.