A lawyer for a Halifax man who strangled an off-duty police officer argues that his mental illness — brought on by the murder — should be a mitigating factor in deciding his parole eligibility.

Christopher Garnier, 30, was convicted in December of second-degree murder and interfering with a dead body in the 2015 death of 36-year-old Catherine Campbell.

The jury found that Garnier strangled Campbell, a Truro police officer, and used a compost bin to dump her body near a harbour bridge on Sept. 11, 2015, after the pair met at a Halifax bar.

The murder conviction carries an automatic life sentence, but a hearing to determine when Garnier will be able to apply for parole is scheduled for Monday in Nova Scotia Supreme Court.

In submissions filed with the court, defence lawyer Joel Pink said his client was diagnosed with post-traumatic stress disorder by a psychiatrist hired by the defence, Dr. Stephen Hucker, and by the psychologist who is currently treating him.

The event that brought on the PTSD: the murder itself.

Hucker, who testified at the trial, said in a report that Garnier suffered from acute stress disorder immediately following Campbell's death, Pink noted.

Garnier repeatedly told the jury he does not remember using a large green compost bin to dispose of the woman's body near the bridge, where it stayed undetected for nearly five days.

"The testimony of Dr. Hucker clearly indicates that there is a strong link between Mr. Garnier's illness and his interference with human remains; therefore, it should be considered a mitigating factor in his sentencing [on that charge]," Pink said in his submissions to Justice Joshua Arnold.

Catherine Campbell, an off-duty police officer, was strangled and her body dumped in a green bin on Sept. 11, 2015. (CBC)

"Courts have consistently held that a sentencing court's application to the principles of sentencing will be influenced by the presence of a mental illness. In such circumstances, the primary concern in sentencing shifts to treatment as the best means of ensuring the protection of the public and that the offending conduct is not repeated."

Parole eligibility for second-degree murder must be set between 10 and 25 years.

Defence seeking 10 years

Pink argues Garnier should serve 10 years behind bars — 10 years for the second-degree murder charge and two years for interfering with a dead body, with the sentences to be served concurrently.

He said Garnier should be on the lower end of that spectrum because he has been described as a "kind, caring person" who has shown remorse for the killing, which Garnier has argued happened accidentally during rough sex. The lawyer also included 31 letters of support from friends and family.

Garnier's parole eligibility hearing was previously set for May, but it was adjourned in part to allow Hucker — who is based in Toronto — to testify.

Crown says Garnier 'treated her remains like garbage'

Meanwhile, the Crown is arguing Garnier should serve 16 years before he's able to apply for parole, calling him "calculating," "manipulative" and "dangerous."

"Mr. Garnier not only murdered Ms. Campbell, he interfered with Ms. Campbell's remains. He demonstrated a callous disregard for Ms. Campbell, and made an attempt to cover his crime," Crown lawyers Christine Driscoll and Carla Ball argued in their submissions to Arnold.

Christopher Garnier writes a note during his police interrogation in 2015. He wrote it to Catherine Campbell's family. (CBC)

"The message should be sent that Mr. Garnier should forever be remembered as the person who stole Ms. Campbell's future for no reason, and then treated her remains like garbage."

The prosecution also noted that Campbell died in a "gruesome way, in that it would not have been quick and immediate."

"Her nose was broken, the cartilage in her neck was broken. He moved her body and concealed numerous pieces of evidence, some of which was never recovered," the submissions said.

"He should be remembered as someone who tried to cover up his crime. His parole eligibility period should reflect the nature of the offence, his future dangerousness, and deterrence."

The Crown has said as many as 10 victim impact statements have been filed as part of the hearing.

Garnier is appealing his conviction in part because he says police interview tactics elicited a false confession.