ALISO VIEJO, Calif. -- A man described as an estranged ex-boyfriend and former business associate of the woman killed in ahas been arrested on suspicion of possessing an unregistered destructive device, the FBI said Thursday. The arrest of Stephen Beal, 59, followed a search of his Long Beach residence by authorities, FBI spokeswoman Laura Eimiller said in a statement.
A neighbor said Beal was an ex-boyfriend of the blast victim, 48-year-old Ildiko Krajnyak, and makes rockets in his garage, CBS News correspondent Jamie Yuccas reports.
Eimiller stressed that Beal was not being held in connection with Tuesday's explosion. She said he was expected to appear in U.S. District Court in Santa Ana later Thursday and that no additional details would be available until a federal criminal complaint is issued.
Beal's Facebook page has many photos of him traveling with Krajnyak, a licensed cosmetologist who owned the day spa where the blast occurred. Their travel destinations included Mexico, Canada and Portugal.
State documents show Beal and Krajnyak as officers in a skin care business called I&S Enterprises.
Authorities have declined to say if they believe the victim was the target.
Remnants of a device were found inside the badly damaged spa where the powerful explosion shook the city of Aliso Viejo, about 50 miles south of Los Angeles. The blast tore a corner off the building that houses medical offices. Two patrons were seriously injured.
"We do not believe this was an accident," said Paul Delacourt, the assistant director in charge of the FBI's field office in Los Angeles. "Although the damage was extensive, there are some components that we have located at the scene of the explosion that are inconsistent with what one might expect to find at this business."
Stuart Davis, who lives a few doors down from Beal's home in Long Beach, said he often saw Beal and his adult son working on large rockets on their front lawn. The son told Davis that they built movie props, he said.
"There would be rockets, but big, like something you'd see in a movie," Davis said.
Beal's wife died six or seven years ago after she fell down the stairs inside two-story home in a tidy middle class neibhorhood, Davis said.
Photos on Beal's Facebook page showed him vacationing with Krajnyak in Cuba, sitting together on the beach and riding jet skis in Mexico and shopping in Portugal.
The Associated Press left messages seeking comment at a telephone number and email listed for Beal and at numbers listed for his representatives on his acting website.
An attorney who previously represented him in a bankruptcy case did not immediately return a phone call seeking comment and an FBI spokeswoman said she didn't know if Beal had an attorney.
Investigators were working to determine a motive for Tuesday's explosion and figure out exactly how the device got to the spa, Delacourt said.
Meanwhile, friends of the victim set up a fundraising campaign to cover her funeral costs and fly her son home from Seattle, where he attends college.
Krajnyak was originally from Hungary and had just visited there, according to her Facebook page and a neighbor. Her Facebook page showed photos from her home country, including a selfie outside the clinic where she trained to become an aesthetician 30 years ago.
Her Orange County business offered services such as facials, waxing and wrinkle treatments.
A voicemail recording at her business said the spa was closed through Monday and would reopen Tuesday, the day of the blast.
Irene White, a friend, read a statement Wednesday on behalf of Krajnyak's family, calling her death "a complete shock." The family asked for privacy as they mourn "a mother, a wife, a daughter and a friend." She said the family is cooperating with investigators.
The two customers injured underwent surgery Wednesday and were expected to survive. A third victim was treated for smoke inhalation.
Search warrants were served at the business and two other locations, including the Long Beach house.
They also searched Krajnyak's house in Trabuco Canyon.
A neighbor there who would only give her first name as Tiffany said Krajnyak lived there with her estranged husband and mother, whom she cared for.
The couple, although separated, continued to live under the same roof, the neighbor said. Court records show they had filed jointly for bankruptcy in 2014 and the case was dismissed and closed Monday.
Attorney Andrew Bisom, who represented Krajnyak and Ronilo Vestil during the Chapter 13 bankruptcy proceedings, said they were far along on their mandated payment plan but hadn't completed it.
Bisom did not know them well and said there was nothing that stood out about them or their case.
The two-story building where the explosion had blown siding off the walls and shattered windows was closed Wednesday as bomb technicians and investigators from the Orange County Sheriff's Department, the FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives sifted through debris.
Pieces of the explosive device recovered were sent to the FBI's laboratory in Quantico, Virginia, to be analyzed, Delacourt said.