In happy times: Ross Merrick and Marika Ninness.

In happy times: Ross Merrick and Marika Ninness. Photo: Facebook

War veteran Ross Albert Merrick once threw his girlfriend, Marika Ninness, across a room with such force that her head damaged a wall and her injured tailbone needed hospital treatment, the Newcastle Supreme Court has heard.

A jury also heard on Thursday that Ms Ninness told hospital staff she had injured herself when falling off a chair, but would later confide in friends that Mr Merrick had "ragdolled" her during an intense argument before Melbourne Cup day in 2013.

Ross Merrick has pleaded not guilty to murdering his girlfriend of eight months.

Ross Merrick has pleaded not guilty to murdering his girlfriend of eight months. Photo: Darren Pateman

Defence counsel Tania Evers had previously told the jury the incident was a "one-off" in which Merrick had pulled Ms Ninness out of bed during an argument, but did not know his own strength.

Just over a month after the "ragdoll" incident, Ms Ninness suffered severe head injuries after being struck by Mr Merrick and falling onto an East Maitland car park during an argument on December 7, 2013.

She died in hospital 13 days later after never regaining consciousness.

Marika Ninness died after 13 days in hospital after she was allegedly punched to the ground.

Marika Ninness died after 13 days in hospital after she was allegedly punched to the ground.

Mr Merrick, now aged 32 and a three-time Iraqi war veteran with the navy, has pleaded not guilty to murdering his 35-year-old girlfriend, arguing he did not intend to hit Ms Ninness, and he had only struck her with an elbow as part of a "conditioned response" to his military training after she had confronted him.

The prosecution alleges Mr Merrick intentionally hit Ms Ninness to either cause death or grievous bodily harm.

The second day of the trial heard from a list of friends and workmates of Ms Ninness, painting a picture of the couple's volatile relationship.

Megan Beukers, who said she was Ms Ninness' best friend since they were aged five, told the court the pair appeared like a normal couple as they first courted while Ms Ninness was living at Ms Beukers' home.

But she said when they moved into their own place at Ashtonfield, the relationship changed.

"He started to get really controlling," Ms Beukers told the jury.

"He didn't want her to talk to a lot of her friends, he would ring her and if he couldn't get her he would ring me.

"He needed to know where she was all the time."

She later added: "He would always want to know where she was, who she was talking to, whether she had spoken to [separated husband David Blackie] that day, what the texts said".

The prosecution said Ms Ninness confided in her about an argument where Mr Merrick had thrown her across a room, the force of her head hitting the wall causing a hole and rendering her unconscious, and had badly hurt her tailbone.

"They screamed at each other a lot, and then he picked her up and threw her, like a ragdoll she told me," she said.

Ms Beukers, a former police officer, admitted during cross examination that she had rung Mr Merrick's employer after Ms Ninness suffered the head injuries and told him: "Would love to send you the full brief of evidence to show you the full facts of the matter".

She admitted she never had a brief of evidence and also confirmed she had written a Facebook post which included: "two more witnesses in our favour have come forward".

A workmate of Ms Ninness', Felicity Freeman, told the court of a work Christmas party where Ms Ninness appeared "agitated" and in a mood "I had not actually seen before".

She suffered the head injuries the following night.

Another workmate, Kristy Hardy, said Ms Ninness had also told her of being thrown into the wall, and that she couldn't tell hospital staff how she had injured her tailbone because "she loved him".

Ms Hardy said Ms Ninness would tell her that she would fight a lot with Mr Merrick, and that he was "an extremely possessive man and didn't let her do a lot of things".

"Her words actually were that the relationship was quite poisonous," she said.

Ms Hardy said Ms Ninness told her she had to change her password on her mobile phone because Ms Merrick would read her messages.

"Marika and I would have the conversation every week; that she loved Ross but she couldn't stay with him," Ms Hardy said.

"It was the possessiveness, the aggression and the abuse she was getting from him."

The trial before Justice Helen Wilson continues.