A Crown prosecutor told a Halifax jury Tuesday that the man accused of murdering off-duty police officer Catherine Campbell lost control the night she died, striking her on the head and strangling her until he heard her last breath.

Christopher Garnier, 29, is on trial in Nova Scotia Supreme Court for second-degree murder and improperly interfering with human remains in the September 2015 death of Campbell. He has pleaded not guilty.

In her opening address to the jury, Crown attorney Carla Ball said Garnier had broken up with his girlfriend and was staying at a friend's place on McCully Street in Halifax the night he met Campbell at the Alehouse, a bar in the city's downtown.

Ball said Garnier and Campbell returned to the apartment, where she said Campbell was murdered.

Ball said Garnier threw out a blood-stained mattress and then put Campbell's body in a green bin, wheeling it through the streets and dumping her under Halifax's Macdonald Bridge.

Christopher Garnier

Christopher Garnier has pleaded not guilty to the two charges he's facing. (Andrew Vaughan/Canadian Press)

A the time of her death, Campbell was a constable with the police department in Truro, N.S. 

The first Crown witness Tuesday was a Truro police dispatcher who asked Halifax police to look for Campbell when she didn't show up to work.

The second witness was a Halifax police officer who checked Campbell's Dartmouth apartment. He said the TV was on, her alarm clock was ringing and nothing was out of place.

The Crown also played security video from Campbell's apartment showing her in the hours before she died. Members of her family who were in the courtroom sobbed as the video played.

The final witness of the day was the cab driver who took her to the Alehouse the night the Crown says she died.

The trial continues Wednesday.

CBC reporter Blair Rhodes live tweeted from the trial.