Long Beach resident Stephen Beal was taken into custody Wednesday evening on suspicion of being in possession of an unregistered destructive device, according to a statement released on behalf of the Orange County Sheriff's Department; FBI; Bureau of Alcohol, Tobacco, Firearms and Explosives; and the U.S. Attorney's Office.
"Mr. Beal is not being charged in connection with the explosion," which occurred Tuesday, the news release said. Three other people were injured in the blast -- two who are expected to survive after surgery and a third person who was treated at the scene.
"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."
Investigators said a device was found when a search warrant was served at Beal's home. They did not describe it in detail.
"You can see there's a street in between our houses so I'm kind of glad of that now," said Linda Brown, who lives near the defendant. "For someone to use an explosive? I don't know what to make of it. It's just very hard to take it all in."
Neighbors described Beal as an ex-boyfriend of Ildiko Krajnyak-Vestil, the 48-year-old Trabuco Canyon resident and spa owner who was killed in the blast. They also said Beal was a hobbyist interested in model rockets.
"He used to build rockets and stuff," said nearby resident Don Westerhoff, "so he was familiar with explosives."
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Beal's wife died in 2008. According to Westerhoff, the circumstances of her death were also suspicious.
"There's too many things that point in the same direction, for me," the neighbor said.
Meanwhile, in the Trabuco Canyon neighborhood where Krajnyak-Vestil lived, people who knew her were tying ribbons around trees, light poles and fence posts in her honor. The ribbons were orange, her favorite color.
Beal's Facebook page has many photos of him traveling with Krajnyak-Vestil. Their travel destinations included Mexico, Canada and Portugal.
State documents show Krajnyak-Vestil and Beal as officers in a skin care business called I&S Enterprises.
People in the #TrabucoCanyon neighborhood where Ildiko Krajnyak lived are putting up orange ribbons in her honor. Orange was her favorite color. She was killed in the #AlisoViejo explosion @ABC7 pic.twitter.com/2yAo1PH0Fc— Greg Lee (@abc7greg) May 17, 2018
He is expected to appear in U.S. District Court in Santa Ana Thursday afternoon.
The Associated Press contributed to this report.