HALIFAX -- Police in Halifax made an unusual request for public assistance Thursday after accusing a former volunteer firefighter of murdering an off-duty police officer last week.

Christopher Calvin Garnier, 27, made a brief appearance in a Halifax courtroom where he was formally charged with second-degree murder in the death of 36-year-old Catherine Campbell, a constable with the Truro Police Force who was reported missing Monday when she failed to show up for work.

Supt. Jim Perrin of Halifax Regional Police told a news conference Garnier was also charged with indecently interfering with a dead body.

He said that charge was laid "because of the cavalier way that Miss Campbell's body was disposed of."

Perrin said police are asking witnesses in Halifax to come forward if they saw a white man in shorts and a T-shirt pulling or pushing a large, green compost bin through the city's north end last Friday around 4:30 a.m. Perrin wouldn't comment on what was in the bin, except to say that it contained evidence.

Investigators believe the victim met the accused last Thursday night at a downtown bar, where Campbell was last seen, Perrin said.

Police allege Campbell was killed hours later at a location on McCully Street in the city's north end.

Her body was discovered just after midnight on Tuesday night, less than a kilometre away in a wooded area near an overpass that leads to the Angus L. Macdonald Bridge, which links Halifax and Dartmouth.

About an hour later, Garnier was arrested during a traffic stop.

Perrin said investigators do not believe Campbell's work as a police officer had anything to do with her death. As well, he said it was unclear whether the two knew each other before they are alleged to have met last Thursday.

"Obviously ... how that meeting took place is something that's still under investigation. But we have confirmed that they were together in downtown Halifax. ... We're continuing to explore whether they knew each other before that."

Campbell's family said she worked as a firefighter in her hometown of Stellarton before joining the police force six years ago in Truro, an hour's drive north of Halifax.

A spokesman for Halifax's regional government confirmed Garnier worked as a volunteer firefighter between October 2009 and February 2011.

Police are not looking for other suspects but more charges could be laid, Perrin said.

Garnier did not speak during his five-minute appearance in court. His case was put over to Sept. 30 to allow the defence time to review evidence. Crown attorney Paul Carver said outside court that he will oppose any request for bail.

Rob Green, branch manager for a Halifax-area fire suppression and safety company, said Garnier started working for the company as a salesman on Monday but was fired Wednesday when he failed to show up for work.

Green said he and staff members at K&D Pratt Maritimes were stunned when they learned of the charges against Garnier, whose widely circulated picture and address listed in court documents matched with the man they just hired.

"My first thought was for the poor family of the deceased woman," Green said in an interview. "I can't imagine, as a parent, how anybody would feel to have their child taken away in a very heinous way."

Green said he met Garnier for only 20 minutes during an initial orientation on Monday.

"It's a bit surreal," said Green, who described Garnier as a soft-spoken man who seemed positive about his new job.

"People in the office were quite shocked. And everybody, without fail, their first consideration was, 'Oh my God, this woman's family.' You just feel terrible. It's awful. It's tragic."

Outside the main police station in Halifax, the Town of Truro flag was raised in honour of Campbell. Halifax Regional Police have also started a book of condolences at their headquarters.