HALIFAX -- A Halifax man accused of killing an off-duty police officer "heard her last breaths" as he strangled her and later dumped her body using a green compost bin, a Crown attorney told a jury Tuesday.

"This case is about a man who loses control," prosecutor Carla Ball said in her opening statement at the second-degree murder trial of Christopher Calvin Garnier.

"He's alleged to have punched and strangled (Truro police Const. Catherine Campbell), and killed her. We allege he then put her lifeless body into a green compost bin and dumped her over a bank."

Garnier, 29, is also charged with interfering with a dead body. He has pleaded not guilty to both charges.

The 36-year-old Campbell's remains were found near Halifax's Macdonald Bridge in September 2015, days after the alleged murder.

Ball told the jury that Garnier -- who was staying with a friend in north end Halifax after breaking up with his girlfriend -- met Campbell at the Halifax Alehouse bar early on Sept. 11, 2015.

Garnier and Campbell left the bar together at about 3:30 a.m., and took a cab back to his friend's place, she said.

Ball alleged that Garnier "hit her in the face and she bled from the head area leaving a stain on the mattress the size of a piece of paper."

"Then, he placed his hands around her neck. You will also hear that he heard her last breaths," she told the jury.

Garnier then "moved quickly" to get rid of any evidence, said Ball.

She alleges Garnier was seen with a mattress. He was also seen pulling a green compost bin towards his friend's place, and then pulling it away from the same address, down towards the waterfront where Campbell's body was found, said Ball.

"Mr. Garnier put his bloody T-shirt and Ms. Campbell's keys in a black garbage bag and tossed (them) in a large garbage dumpster across the street from (his friend's) flat," said Ball.

Garnier had told his friend in a text message that he had been hanging out with an off-duty cop, and that he threw out the mattress because he vomited on it, said Ball.

By the following Tuesday, Garnier was under surveillance by police and was observed driving by the area where the body was dumped, Ball alleges. She said he drove home and was arrested.

"When Mr. Garnier exited the vehicle, police observed a rope, tarp, a backpack, gloves and a gas can in the passenger seat. They also found bungee cords and his passport," Ball told the jury.

None of the allegations have been proven in court.

The jury also heard testimony from three witnesses on Tuesday, including a Truro police dispatch supervisor who asked Halifax Regional Police to check on Campbell after she did not report to work on Sept. 14, 2015.

The officer who conducted the check at her Dartmouth apartment, Const. Stuart McCulley of Halifax Regional Police, also took the witness stand.

He told the jury he entered the apartment after a building supervisor opened the door and found it to be very neat and tidy. He said nothing appeared to be out of place, but the alarm clock was going off. Hospitals were then called to see if she was a patient, he said.

McCulley said he later reviewed video footage from her apartment building from Sept. 13, 2015, but Campbell was not observed on camera.

"Something didn't feel right," said McCulley.

The jury was later shown video from inside her apartment building. McCulley identified Campbell as a woman in police uniform in an elevator, and also identified her as a woman dressed in civilian clothes leaving the building in the early hours of Sept. 11, 2015.

Members of Campbell's family sobbed as Campbell was shown in what are alleged to be her last hours alive.

Under cross-examination by defence lawyer Joel Pink, McCulley said he had never met Campbell, but deducted it was her seen leaving the building in civilian clothes from the earlier footage of her in uniform.

A taxi driver also testified that he picked Campbell up in the early hours of Sept. 11, 2015, and drove her to the Halifax Alehouse.

The 14-member jury was chosen Monday and Tuesday in Nova Scotia Supreme Court. Twenty three days have been set aside for the trial.