The boyfriend of a young woman who was stabbed to death in Nova Scotia’s Pictou County in 2011 returned to the stand in the Supreme Court of Nova Scotia in Pictou on Thursday.

Mason Campbell was one of the last people to speak to 19-year-old Amber Kirwan before she vanished the night of Oct. 8, 2011.

Campbell said on Wednesday that there had been a party that night at the Pictou Landing apartment he shared with Kirwan.

After a night of drinking and socializing with some friends and work colleagues, Campbell said Kirwan decided to accompany some of them to a pool hall and bar in New Glasgow.

Campbell said he stayed behind with some others to socialize and to clean up the apartment but didn’t end up going to the bar.

Later that night, he spoke to Kirwan and agreed to pick her up at Big Al’s convenience store, which is less than a five-minute walk from the pool hall.

When Crown prosecutor Bill Gorman asked why he didn't go to the pool hall to pick up Kirwan, Campbell said he was worried about police being in front of the popular night spot.

Campbell was back on the witness stand on Thursday, where the defence pressed him about the night Kirwan disappeared.

Defence lawyer Mike Taylor asked Campbell why he didn’t tell police the real reason he arranged to meet Kirwan at Big Al’s, and not at the pool hall, when he was first questioned about her disappearance.

Campbell testified it was because he didn’t want to be caught by police as he had smoked marijuana, had a few drinks and didn’t have insurance at the time.

He said he felt those details were irrelevant to the fact that Kirwan never showed up as they had arranged and hadn’t been seen since.

"The importance of any discrepency or any of the evidence really is something for the jury to determine. I simply wanted to highlight things that I felt were of some significance," said Taylor.

Kirwan’s body was found in a shallow grave off a rural road in Heathbell, N.S. about a month after she disappeared.

Christopher Alexander Falconer, 31, is charged with first-degree murder in her death. He has pleaded not guilty.

Campbell told the court he didn’t know the accused and neither did Kirwan.

He became emotional as he described when his mother told him Kirwan’s remains had been found.

“It was like my whole world came crashing down,” he said.

"He was worried about Amber and, especially by the next day, he was frantic looking for her," said Crown attorney Patrick Young.

Other Crown witnesses to take the stand included a husband and wife who live a few kilometres from the accused in Heathbell, N.S.

They testified seeing a suspicious car near their home and said they felt compelled to search the area. They also told the court they were shocked to find leggings and earrings in the woods that were similar to ones Kirwan had been wearing the night she disappeared.

They called police and the discovery launched a forensic and ground search of the Heathbell area.

Kirwan’s body was found about two weeks later, naked and bound at the wrists.

Two police forensic officers also took the stand on Thursday. Officer testimony will continue Friday.

With files from CTV Atlantic's Kelland Sundahl and The Canadian Press