The jury in the murder trial of Christopher Garnier watched about 2½ hours of a 9½-hour video of his police interrogation following his arrest in the death of off-duty officer Catherine Campbell.

RCMP Cpl. Jody Allison testified Monday that he conducted the interview at the RCMP detachment in Lower Sackville, N.S., on the afternoon of Sept. 16, 2015.

The video shows Garnier — dressed in a grey T-shirt and pants — in a plain, windowless room with two chairs, a desk and a computer monitor. For the first 20 minutes, Garnier said virtually nothing, other than to ask if his father had been notified.

Garnier is later seen sobbing and sniffling on the video as Allison tells him that he's not a bad guy.

"I don't think it was your intention for it to end up the way it did," Allison said.

Catherine Campbell, an off-duty police officer, was strangled and her body dumped under Halifax's Macdonald Bridge. (CBC)

The Mountie also refers to Garnier's background in occupational health and safety during the interrogation.

"The safety-minded people? They are the ones that have a good heart," Allison said in the video.

During the hours-long interview, Allison tells Garnier his movements could be tracked by his phone, that police have already interviewed his girlfriend, Brittany, and plays him video taken from outside the apartment on McCully Street where police allege Campbell was killed.

'How come you snapped?'

He also shows Garnier photos of Campbell when she was alive, and then a picture taken after her body was discovered.

At one point, Allison describes the case police are building against Garnier as a "slam dunk" and urges him to talk.

Allison also asked Garnier in the video if he had sex with Campbell. Garnier at first said no. When Allison asked again if he had sex with Campbell, Garnier said, "I don't think."

"So how come you snapped?" Allison asked. "There has to be some reason."

At the end of the day, the Crown said Garnier's girlfriend, Brittany, was not aware he was being investigated until police woke her up on the morning of Sept. 16, 2015.

The Crown said she wasn't aware Garnier had taken her vehicle, a white Ford Edge, while she was asleep.

Toiletries, passport seized

Garnier, 30, is on trial in Nova Scotia Supreme Court in Halifax for second-degree murder in Campbell's death and for interfering with human remains. He has pleaded not guilty to both counts.

In earlier testimony today, the jury was told police officers found toiletries, clothes and Garnier's passport inside a backpack seized from the Ford Edge he was driving when he was arrested.

The court has also heard officers found a green tarp, yellow rope and a new pair of work gloves in the front passenger seat. Sgt. Andre Habib testified he photographed everything in the car, without being sure what was significant.

A police evidence photo of a green tarp in the front passenger area of a vehicle is seen at Nova Scotia Supreme Court in Halifax on Friday, Dec. 1, 2017. (Andrew Vaughan/Canadian Press)

Wearing purple latex gloves, Habib held up items for the 14-member jury to see Monday, including a hair clip, a strapless dress and a strapless bra — all items Campbell was wearing when her body was found.

The Crown alleges Campbell, a 36-year-old constable with the Truro Police Service, and Garnier met in the early hours of Sept. 11, 2015, at the Halifax Alehouse, a downtown bar, and then returned to the McCully Street apartment.

The Crown has argued that Garnier punched and strangled Campbell in that apartment, putting her body in a green compost bin and dumping it under Halifax's Macdonald Bridge, where she was found several days later.

The jury has heard police combed through the apartment during their investigation into Campbell's disappearance. The mattress for the couch was missing.

Habib testified police never found the mattress.

The case is scheduled to run until Dec. 21, with a verdict expected just before Christmas.

The CBC's Blair Rhodes was live blogging from court.