The family had been living at the home for three years, but they were forced into foreclosure when Walder lost his job, police said.
His wife, Martha Walder, testified in Los Angeles County Superior Court that her husband’s demeanor changed after that.
The couple were more than a $1 million in debt and were talking about divorce, police said.
Brian Walder’s attorney, Stephen Kahn, said his client was innocent and would never hurt his children.
“He loves his kids,” Kahn said.
The first responding officer, a fire captain and Martha Walder have all testified so far this week.
Glendale police arson investigator Miguel Porras testified that he noticed fires had been started at two spots in the home’s patio area — a pillar and the fire pit.
“I smelled what smelled like gasoline,” Porras said.
The odor of gasoline was strong in the fire pit and on the middle and bottom portions of the wood pillar, he said.
Fire from the wood pillar radiated onto a nearby tree and caused the patio cover to collapse.
Flammable liquid on the pillar and an intentionally set flame was the only likely cause of such a blaze, Porras added.
But Kahn claimed that the fire was accidentally set when Brian Walder tripped while smoking a cigar on the patio, causing an alcohol bottle and the gasoline container to spill on the ground. The cigar then ignited the gasoline.
“We believe this case was an accident,” he told the jury.
Porras testified that the odds of a cigar setting gasoline ablaze were “highly unlikely.”
