HALIFAX -- A tarp, work gloves and rope were among the items found in a car Christopher Garnier was driving when he was arrested in the death of an off-duty police officer, an investigator told a jury Wednesday.

Sgt. Kenneth Burton told Garnier's murder trial he was part of a team that had Garnier, 29, under surveillance in the days after Const. Catherine Campbell went missing.

Burton said he followed a white Ford Edge from a home in suburban Clayton Park to central Halifax in the early hours of Sept. 16, 2015, in the area where Campbell's body was found.

The Crown has alleged Garnier punched and strangled the 36-year-old Truro, N.S., police officer inside an apartment and used a green compost bin to dump the body in thick brush on a steep embankment near the Macdonald Bridge.

Burton said the car returned to Clayton Park and the driver was stopped by another officer. He says Garnier was placed under arrest and that he saw a green tarp, work gloves, a backpack, yellow rope and tape in the car.

Under cross-examination by defence lawyer Joel Pink, the Halifax Regional Police officer told the Nova Scotia Supreme Court jury he did not know what Garnier's job was, or whether any of the items could have been related to it.

Garnier has pleaded not guilty to second-degree murder and interfering with a dead body.

Garnier had met Campbell at a downtown bar on Sept. 11, 2015, and the defence put forth a hypothetical scenario on Tuesday suggesting she died during a consensual sexual encounter after encouraging Garnier to choke her.

Also Wednesday, a witness told the jury he saw a man rolling a compost bin towards the wooded area where Campbell's body was discovered, days after Garnier allegedly killed Campbell.

David Yeo said he was having a cigarette on his second-floor balcony, which overlooks Barrington Street near the bridge, just after 5 a.m. on Sept. 11, 2015, when he saw something "very peculiar."

"I saw some strange activities outside," said Yeo, adding that he left the balcony only for a few minutes to retrieve a coffee.

Yeo said he watched a man "struggling" with a compost bin as he pulled it across Barrington towards a tree line.

He said he saw the man -- who he identified as Garnier -- coming back about five minutes later, still dragging the compost bin.

"He was throwing it around -- cursing and swearing ... He wasn't struggling with it (anymore)," said Yeo.

The jury has heard from two other witnesses who testified they saw a man rolling a compost bin down Agricola Street and North Street towards the harbour.

RCMP toxicologist Christopher Keddy testified Wednesday that Campbell had alcohol in her system at the time of her death.

He agreed that if witnesses have testified Campbell was not showing signs of intoxication, it would be fair to say she "had developed some degree of tolerance to the effects of alcohol."

Nova Scotia chief medical examiner told the jury Tuesday that Campbell died of strangulation, and suffered head injuries including black eyes and a fractured nose. Bowes said her body was found face down and partially decomposed.