Just four days after Christmas, 53-year-old Edmonton man Phu Lam shot and killed four women, two men, and two children before turning the gun on himself.

As investigators struggle to find answers in what the city’s mayor has described as "a devastating case of domestic violence," experts are offering their insights to help better understand Lam’s actions.

University of Toronto professor Katreena Scott, the Canada research chair in family violence prevention and intervention, says that while the killings are shocking and saddening, existing studies can help explain what took place.

“We know a lot more about some of the risk factors involved in homicides and suicides and this kind of linked offence,” Scott said.

Some of the factors to look for, she says, are obsessive behaviour, depression in the killer, and an escalation of violence prior to the murder. Threats of suicide or harm towards the victim, as well as a history of violence, can also be warning signs.

Scott said that about 75 per cent of suicidal homicides share seven or more of these “risk factors.”

“When you look backwards and piece together the information, you realize that there are many, many things that are risk factors for that family,” she said.

Scott said police usually know about these risks in the cases of people with records, but that others have to be made aware to prevent these situations from repeating themselves.

Timeline of events

Investigators say Lam shot one woman at a south Edmonton home Monday night at about 6:50 p.m.

Officers were then called to a north Edmonton home on two separate occasions. The first time, the caller asked for help with a “depressed” and “overly emotional” male family member, but no one answered the door when police arrived. A second, different caller phoned police after midnight, and officers entered the home to find seven dead, including two children.

The next morning, police surrounded a Vietnamese restaurant in nearby Fort Saskatchewan and found the suspect dead inside at about 9 a.m.

Lam was a maintenance worker at the VN Express, according to the daughter-in-law of one of the restaurant’s owners.

A black SUV found at the restaurant had also been spotted at the south Edmonton home where the first victim was killed, police said.

The 9mm handgun used in the deadly rampage was legally registered in B.C. in 1997, but was reported stolen in 2006.