HALIFAX -- An RCMP investigator testified Wednesday about the planning a former soldier undertook -- including researching weapons online -- before he shot his family and himself over three years ago.

Cpl. Gerry Rose-Berthiaume, the lead investigator in the Lionel Desmond case, testified Wednesday at a public inquiry in Guysborough, N.S.

Among other things, the inquiry is examining whether Desmond had access to mental health and domestic violence services -- and whether he should have been able to buy a gun on Jan. 3, 2017, the date of the killings in Upper Big Tracadie.

The investigator said family members told him the veteran had struggled to cope after returning from Afghanistan in 2007, and had conflicts with his spouse, Shanna, that seemed to spiral further out of control after a New Year's Eve incident.

The Mountie said "certain things would just set (Desmond) off," and he told the inquiry that Desmond became embarrassed and upset after driving Shanna's new truck off an icy road that evening.

Rose-Berthiaume said family members told investigators that Desmond remained distressed after the incident, and there were tensions through the night until Shanna asked him to leave her home.

"Based on the investigation, I believe, and the investigators believe, this (incident) set this chain of events in motion," he said.

The officer said that on Jan. 1, Desmond checked himself into St. Martha's Regional Hospital in Antigonish, N.S., and was released after spending a night there and being seen by two doctors.

Rose-Berthiaume said Desmond spent Jan. 2 packing his clothes and bringing them to a relative's home, but on Jan. 3 he drove into Antigonish and, after making a medical appointment, purchased a gun at a hunting and fishing store between 3 and 4 p.m.

The inquiry has previously heard testimony that Desmond had a legal right to buy an SKS 762, which the first officer on the scene described as a "military style carbine."

The officer said Desmond had driven his vehicle onto a rough road nearby his wife's residence and approached the home on foot. "He took steps to conceal he was actually going there," Rose-Berthiaume said.

He said that in his opinion the killings constituted first-degree murder.

"The searches of the (weapons) websites, the purchasing of the gun, the placement of the vehicle, the stabbing of (Shanna's car) tires ... speaks to me of deliberate planning and deliberation leading up to the event itself," he testified.

Gilles Marchand, an RCMP digital forensics expert, testified later that cell phone analysis indicated Desmond had browsed multiple websites for weapons information.

The inquiry also heard of text messages that Desmond sent to his wife on New Year's Day, asking if he could return and apologizing for previous arguments.

"I'm sorry I put my hands on you, I would never hit you," one text said.

But Rose-Berthiaume testified that when Desmond set off to his wife's home on Jan. 3, he had changed into a full camouflage outfit.

The officer said it's possible Desmond hadn't expected to find his daughter Aaliyah and mother Brenda at home, citing a phone call the veteran made to check if his daughter was at school.

The officer also testified that Brenda, Lionel's 52-year-old mother, called her brother George Desmond at about 6 p.m. and told him, "You have got to get down here right away, the boy just shot his wife."

The officer said George Desmond told him by the time he had arrived approximately 10 minutes later, all four deaths had already occurred.

Rose-Berthiaume testified Lionel Desmond's lifeless body was found on the floor of the home, with a rifle lying across his outstretched arm and a single bullet wound.

The body of Desmond's mother Brenda had one bullet wound, as did the body of his 10-year-old daughter Aaliyah. Shanna had three wounds, the officer testified.

The inquiry continues Thursday.

This report by The Canadian Press was first published Jan. 29, 2020.