HALIFAX -- A Montreal-born yoga instructor had told friends she wanted to break up with her boyfriend hours before he allegedly murdered her and tried to kill himself inside her Halifax-area home, a Crown lawyer said Wednesday.

During her opening statement at Nicholas Butcher's second-degree murder trial, prosecutor Tanya Carter alleged the 35-year-old man "couldn't be without Kristin Johnston, and killed her."

"The evidence is not complicated. Kristin's life ended in tragedy, and the evidence points to Mr. Butcher committing murder," Carter told the Nova Scotia Supreme Court jury.

Carter said the evidence will show that the pair were dating in March 2016 when Johnston, 32, decided to end the relationship.

Butcher, a graduate of Dalhousie University's law school, had been living with Johnston for a short time at her home in Purcells Cove, she said.

Carter said on the evening of March 25, 2016, Johnston was spending time with friends at a trendy north end Halifax bar called Lion and Bright.

"She talked about her plans for the future, her difficulty with finding the best way to break up with Mr. Butcher and her desire not to go home that night," said Carter.

Later that evening, Johnston went to a friend's house nearby. However, Butcher found out where she was and went there, speaking with Johnston before leaving the house without her, the Crown lawyer said.

"Mr. Butcher went to the same house again a couple of hours later, unhappy with Kristin's continued presence," she said.

Johnston's friend briefly left the house, and "that was the last time Kristin was seen alive," Carter said.

When the friend returned, Johnston and Butcher were gone.

The next morning, Butcher called 911 and told the call taker he had killed his girlfriend and tried to kill himself, said Carter.

She said the medical examiner will testify that Johnston had 10 wounds on her neck, and that her death was caused by sharp force.

Butcher has pleaded not guilty to second-degree murder.

Wearing a navy suit and glasses, Butcher sat quietly next to his lawyers Peter Planetta and Jonathan Hughes during the proceedings Wednesday, occasionally jotting down notes on a pad of paper.

Johnston, who had opened a Bikram yoga studio in downtown Halifax, had a reputation as a kind and determined businesswoman with what friends described as a "magnetic" personality.

Later Wednesday, the Crown called Cameron Dennison, Johnston's brother-in-law, to the stand.

Dennison told the jury that the months leading up to her death were challenging for Johnston, as her business was failing. She was in the process of shutting the studio down at the time of her death, he said.

During a family trip to Florida in early March 2016, Johnston spoke to Dennison about her relationship with Butcher, he said.

"She wasn't happy," Dennison told the jury, occasionally becoming emotional during his testimony. "Her intention was to break up with him, she just wasn't exactly sure how to do it."

Dennison said he believed the pair had dated for about a year in total. He spoke about a previous time Johnston had ended her relationship with Butcher, but that he pleaded with her to take him back.

"She was a very compassionate person so I think she felt bad," he said.

Dennison said the last time he saw Johnston alive was at a Florida airport, where the family was seeing her off to meet up with a friend in Costa Rica.

He said Johnston's plan once she returned from that trip was to leave Halifax and move to Tofino, B.C., to live with himself and her sister, who was pregnant at the time.

Dennison told the jury that Butcher was struggling to find articling work and had briefly moved into Johnston's house while she was away in Florida and Costa Rica because he was having trouble paying his rent.

But under cross-examination, Planetta pointed out that Dennison had told police Butcher lost his lease of his apartment, not that he was having trouble paying his rent.

Dennison agreed he provided more information on the stand Wednesday than what he told police via a Skype interview two years ago.

He said he felt at the time that the cops would get more information from his wife, and was surprised they wanted to speak to him at all.

The Crown has said it expects to call about 40 witnesses.

The trial resumes Thursday.