A teenager accused of murder claimed her boyfriend was being "dramatic" shortly before he was killed at the couple's apartment.
Rikki-Lee Simeon has denied murdering her partner Brendon Hamilton, 21, who died after being stabbed in the neck at his Dominion Rd flat in May 2019.
On Monday, forensic pathologist Dr Rexon Tse told the High Court in Auckland the fatal injury could have resulted in theory from many scenarios, including a struggle.
Jurors heard the 75mm injury pierced a lung and carotid artery, narrowly missing Hamilton's collarbone.
It was unclear how strong the force of the stab was. Tse said when a blade struck a person's collarbone, sometimes a victim would suffer only superficial injuries.
Instead, the pathologist said Hamilton suffered injuries which typically caused a person not to die immediately, but after several minutes.
Earlier in the trial, jurors heard Simeon turned up at the Mt Eden crime scene and spoke to a police sergeant after Hamilton was found dead on Saturday May 18.
Jurors heard the sergeant asked Simeon where her shoes were, and she'd responded with confusion.
The jury was shown a police interview Detective James Copeland recorded shortly after Simeon's arrest.
After a few moments during the interview, Simeon claimed she hadn't heard anything Copeland had said.
"I can't hear but I can read," she added.
"It looks like other police officers have communicated with you and you've been able to respond," the detective replied.
Simeon then buried her head in her arms on the table in the interview room.
Copeland said Simeon had told the sergeant at the crime scene she'd stabbed Hamilton.
"Yes, I did, by accident," she replied in the interview room.
But Copeland said Simeon also told the sergeant she hadn't stabbed her boyfriend at all, and instead Hamilton had tried to stab her.
"We just had this argument and then he tried to pull a knife on me," Simeon told Copeland.
She told the detective the couple had been together for four years.
"I just don't like the fact that he tried to take over me and stuff."
Simeon told Copeland her partner was being "dramatic".
She said her boyfriend's mood had abruptly changed.
"It was just like a twist. He switched like that," she said with a snap of her fingers.
Another detective analysed about three months of phone records for Simeon, Hamilton and some of the couple's relatives and friends.
Jurors heard Hamilton repeatedly spoke of being in financial trouble.
"I'm getting done for the bills, bro," Hamilton said in one text to an associate.
Bank statements were also obtained.
Defence counsel Paul Borich QC said a month of statements showed Simeon promptly transferred all or almost all incoming payments, including Winz benefits, to Hamilton.
The defence has said jurors would have to know what happened in the Dominion Rd apartment before even contemplating whether Simeon had murderous intent.
Crown prosecutor Kirsten Lummis previously told jurors Hamilton had complained about Simeon being abusive.
She said the relationship was peppered with violence and Simeon once attacked Hamilton with a baseball bat.
The court has been told Simeon and Hamilton had a baby together but the child stayed with Hamilton's mother in Rotorua.
The trial before Justice Neil Campbell continues.