CASA GRANDE, Ariz. -- Autopsy reports have been released for a married couple and their son who were found dead in their incinerated Pinal County home in December.
The reports showed that 51-year-old Dr. Joyce Bonenberger and her 11-year-old son, Trevor Brough, had drugs in their system.
Bonenberger had morphine and codeine in her system and a skull fracture on the back of her head.
"There was no smoke inhalation in her lungs, which means that she was deceased before the fire even began," Pinal County Sheriff's Office spokesman Tim Gaffney said.
Bonenberger's husband, 50-year-old Dennis Brough, died of smoke inhalation and did not test positive for any drugs.
Trevor also succumbed to the smoke, but Gaffney said there is no logical reason why a child would have Narcan in his system.
"From the very beginning, this fire's been suspicious," he said.
Firefighters and sheriff's deputies responded to the fire in the Desert Highlands subdivision near Paseo del Sol and Henness roads about 6:30 a.m. Dec. 13. They found the home fully engulfed and later located three burned bodies, which had to be identified with dental records.
Dennis Brough's body was found in the garage, Bonenberger's in the master bedroom, and Trevor's in another bedroom.
But arson investigators are still trying to determine the cause and origin of the blaze, which leveled the four-bedroom upscale home northeast of Casa Grande.
Meanwhile, sheriff's investigators are looking into the business and financial dealings of the family. They are focusing on Bonenberger's private practice for which her husband worked as the office manager.
"We're not going to jump to any conclusions," Gaffney said. "This is one piece of the investigation."
Gaffney said it's unlikely criminal charges will ever be filed but investigators owe it to the family's relatives and friends to figure out what happened.
"It's hard for me to even go there, knowing them," said family friend Rev. Ben Seller of First Presbyterian Church. "We ask for prayers and peace for everybody involved in this because it's just a horrible story and tragedy we've been mourning for the last two months."
Seller had previously described the family as loving and extremely close-knit.
In addition to having a private practice, Bonenberger served as chief of surgery at Casa Grande Regional Medical Center for nine years. She joined the hospital's staff in July 1999.
The hospital said she helped pioneer a breakthrough treatment for early-stage breast cancer.