A Southern California man who was arrested recently for allegedly planting a bomb in a package that killed his former girlfriend on May 15 lost his wife under "mysterious circumstances" a decade ago, reports said.

The explosion in a spa Stephen Beal owned with his ex-girlfriend, Ildiko Krajnyak, killed the woman and injured three others. Beal was arrested later. 

Beal’s wife Christine died in 2008 after she fell down from the stairs at their home while carrying a heavy piece of furniture with her husband. In the initial report, pancreatitis and an electrolyte imbalance were revealed to be the cause of her death as she reportedly fell on her pelvis and hip area.

There were no signs of foul play but it was not clear if the death was due to trauma, the Los Angeles County coroner's office said at the time. Her postmortem report claimed that after his wife’s death, Beal was "uncooperative, not wanting to 'reveal' information to the hospital staff about her,” reported ABC News.

Benzodiazepine, a medication commonly used for anxiety, was found in her system during a toxicology screening. The screening also showed her blood lead level to be 24 times greater than the number set by the National Institute for Occupational Safety and Health.

The autopsy report called it "a mysterious case" as it couldn’t conclusively say whether the fall contributed to her death. The report suggested that "Death is probably natural, maybe trauma contributed but this is not known.”

Following this, a life insurance company had denied him his claim stating the death was not accidental. Beal then filed a lawsuit against the company and won $550,000.

GettyImages-899456288 Southern California man was charged with planting a bomb in a package that has killed his former girlfriend. In the photo, firefighters put out a major house fire on Prospect Avenue in the Bronx borough of New York City, Dec. 28, 2017. Photo: Amir Levy/Getty Images

Beal was on Tuesday charged with having an unregistered destructive device in his house and is in custody awaiting a court appearance in a federal court. FBI agents are investigating the bomb blast inside a day spa owned by his ex-girlfriend, Ildiko Krajnyak, that killed her. The spa was located in a medical office building in Aliso Viejo, about 80 kms south of Los Angeles.

They first met online in June 2016 and dated for about 18 months. Beal’s friend and neighbor Stephen Young rejected suspicions about the death of Christine, calling it just a tragic accident.

He also said he couldn't imagine Beal doing anything violent.

"If there was anything unusual about that she certainly had time to confide in a nurse or someone like that," Young said. "I have no doubt it was truly an accident. I think he really suffered from the loss of his wife for several years."

Young also said Beal frequently spoke about Krajnyak and they both seemed to be very happy. They broke up this year due to differences over finance and exclusivity.