MIRAMICHI, N.B. -- A forensic pathologist cast doubt Wednesday at the trial of a New Brunswick man accused of killing his 16-year-old cousin that the girl's death should be ruled a homicide.

Dr. David Chiasson of the Hospital for Sick Children in Toronto told the trial of Curtis Bonnell that he disagrees with the homicide determination.

"I think at best it is undetermined," Chiasson said in the Court of Queen's Bench.

He said there was no trauma on the body and no cause of death identified in the toxicology report.

"I don't think we have enough information to make a homicide determination," he said.

"You have a young woman buried in clandestine circumstances. I believe that is why a homicide determination was made."

Bonnell, 32, has pleaded not guilty to first-degree murder at the trial in Miramichi, N.B.

The defence finished presenting its case on Wednesday.

On Monday, Bonnell testified that he had been drinking heavily and snorting cocaine on the night of Sept. 4, 2009, and blacked out.

He said he woke up the next morning in his pickup truck and found Hilary dead on the seat next to him, but he didn't know how she died.

Bonnell said he panicked and took her body to the woods, then returned the next day to bury her.

The trial has heard the girl went missing after attending a house party on the Esgenoopetitj First Nation.

Chiasson, who was called as a witness by defence lawyer Gilles Lemieux, testified that he didn't see any of the injuries he would expect if someone had been smothered with a hand over their mouth and nose.

Hilary Bonnell could have died as a result of "positional asphyxia," he said, which can happen when someone is intoxicated and they get in a slumped position that constricts their airway.

"It is a reasonable consideration in this situation," Chiasson said.

Under cross-examination by Crown attorney Bill Richards, Chiasson said the girl's death "remains criminally suspicious."

He also agreed with Richards when he asked if someone sitting on Hilary's chest while putting their hand over her mouth would have increased the chance of asphyxia.

Before he finished his testimony Wednesday, Bonnell told the court that a confession he made to police on Dec. 2, 2009, about sexually assaulting and killing his cousin is false.

Reading from transcripts of police interviews, Richards reminded Bonnell of what he told police.

"You told (an officer) you sexually assaulted her in your backyard and sat on her with your hand over her mouth," Richards said.

"They wanted a false confession. They got it," Bonnell replied.

Bonnell also dismissed a suggestion from Richards that a picture showing the position of the girl's clothing taken before an autopsy indicates she had been in a struggle.

"I suggest she was fighting for her life and the skirt got shifted around," Richards said.

"No, that never happened," Bonnell said.

The girl's mother, Pam Fillier, sobbed in court as the picture was discussed.

Richards said Bonnell told police that he had hit Hilary a couple of times and then held her mouth.

"I said a lot of lies. I just lied about everything," Bonnell said.

The trial was delayed for a few hours on Wednesday after Bonnell was taken to hospital. Outside court, Lemieux said his client complained of numbness and tightness in his chest.