Four years after an explosion tore through part of a north Edmonton neighbourhood, leaving four dead and dozens of homes damaged, a fatality inquiry into what happened that day in 2010 is underway.

On Monday morning, former fire investigator Les Holzman spoke – and said the damage caused by the June 20, 2010 blast was too significant to identify where it started, but investigators found evidence that a gas line had been tampered with.

However, Holzman said there was no indication that someone planned to set off an explosion, he suggested whoever tampered with the line meant to commit suicide by inhaling the natural gas.

Later in the day, allegations of abuse came to light with accounts of the on-again, off-again relationship between two of the people found dead after the blast.

Investigators had found a home in the area of 180A Avenue and 91A Street had been tampered with. It was determined Cathie Heard had been strangled by her common-law husband Dwayne Poirier in that home before the explosion.

Outside of court, Heard’s father talked to CTV News – Chris Robinson said he had warned his daughter to leave her abusive relationship.

“She was relating to me verbal abuse, verbal abuse in front of the kids, berating her in front of the kids, bringing up issues of her sexual abuse in front of the kids,” Robinson said.

Robinson also told the inquiry that the pair took out a number of restraining orders against each other, but always ended up back together.

The couple’s next door neighbours, Craig Huber and Brad Winter were killed in the explosion as well.

Family members of those two roommates were also present Monday.

“My son had a daughter and I feel like I have to do this for her,” Huber’s mother Donna Huber said. “I just don’t understand how something like this could happen; it’s heartbreaking for [his daughter].”

“His death was a part of his life and I need to know everything I can,” Debbie Winter, Brad Winter’s mother, said.

The deaths of Huber, Winter and Heard were all found to be homicides – Poirier was also killed.

In total, forty homes were affected, and the blast caused $3.5 million in damages.

A fatality inquiry is not meant to lay blame, but to result in recommendations to prevent future deaths – during this inquiry, doctors, mental health workers, and experts on family violence and sexual assault are expected to speak.

With files from Brenna Rose