CONWAY, ARK (AP) — An Arkansas woman who adopted her granddaughter after her son’s death in Iraq stabbed the 7-year-old girl in the chest and then set fire to their home in an apparent murder-suicide, authorities said Monday.

Janice Robbins, 63, left a suicide note in her pickup truck before killing her granddaughter, Abby Robbins, and herself on Saturday, Faulkner County sheriff’s spokesman Maj. Andy Shock said. In the note, she wrote that she didn’t want to leave the girl behind.

Robbins stabbed the girl once in the chest, but it was the smoke from the fire, not the stab wound, that killed Abby and her grandmother, the county coroner said.

“We can’t speculate at this point whether or not they were conscious … but we do know they were alive during the time of the fire,” said coroner Patrick F. Moore.

Authorities found a gas can next to each of the bodies inside the lakeside home, which was engulfed in flames by the time firefighters arrived early Saturday morning.

Abby’s father, Army Staff Sgt. William T. “Terry” Robbins, was shot and killed by a fellow soldier in Iraq in 2005 during a dispute over alcohol.

Sometime after his death, Janice Robbins adopted Abby, with the process becoming final in 2010.