The Latest on a deadly explosion at a Southern California office building (all times local):

3:30 p.m.

The former boyfriend of a woman killed in an explosion at a California office building has made his first appearance in court.

Stephen Beal appeared Thursday in federal court in Santa Ana.

The 59-year-old Beal was handcuffed and only spoke to answer questions from the judge.

He was charged with possessing an unregistered destructive device after federal agents searched his home following the deadly bombing in Aliso Viejo on Tuesday. Beal hasn't been charged in connection with the bombing.

His attorney declined to comment after the court hearing.

Investigators said they found two improvised explosive devices, three firearms and other explosive materials in Beal's home.

Authorities say his former girlfriend, 48-year-old Ildiko Krajnyak (IL-di-koh KRY-nyak) was killed when the bomb went off as she opened a package inside the day spa she owned with Beal.

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3 p.m.

A mother and daughter injured during an explosion at a California day spa said the bomb went off as the spa's owner opened a package.

Their description was included in documents released by federal prosecutors on Thursday.

One of the women said she watched the package explode as 48-year-old Ildiko Krajnyak (IL-di-koh KRY-nyak) opened it Tuesday inside an office building in Aliso Viejo.

Authorities said Krajnyak's former boyfriend called police about two hours after the explosion when his current girlfriend told him about the explosion.

They said the man, Stephen Beal, allowed investigators to search his home, where they found two improvised explosive devices, three firearms and other explosive materials.

Beal is awaiting a court appearance after being charged with possessing a destructive device. He hasn't been charged in connection with Tuesday's explosion.

Nathan Beal said his father built sport rockets fueled by a propellant that is legally available at specialty hobby shops.

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2:20 p.m.

Prosecutors say federal agents found two improvised explosive devices while searching a home owned by the former boyfriend of a woman killed in an explosion at a Southern California office building.

Stephen Beal was charged Thursday with possessing an unregistered destructive device and was awaiting a court appearance in federal court in Santa Ana.

He has not been charged in connection with Tuesday's explosion in the city of Aliso Viejo.

Beal's son, Nathan Beal, told The Associated Press that his father had been in a relationship with the woman who was killed, 48-year-old Ildiko Krajnyak (IL-di-koh KRY-nyak). He said they had recently broken up.

Two patrons at Krajnyak's day spa were seriously injured.

Beal's attorney, Isabel Bussarakum, did not immediately respond to a telephone message seeking comment Thursday.

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12:04 p.m.

A neighbor of a California man arrested in connection with the investigation of a deadly explosion says his friend spoke fondly about the blast victim, whom he had dated.

Steven Young of Long Beach says 59-year-old Stephen Beal is helpful, never visibly angry and spoke often of 48-year-old Ildiko Krajnyak (IL-di-koh KRY-nyak), a cosmetologist killed when a device exploded Tuesday at her day spa in Orange County.

The FBI announced Thursday that Beal was arrested on suspicion of possessing an unregistered destructive device after his home was searched in connection with the explosion investigation. The FBI stressed that Beal has not been charged with involvement in the blast.

Young says he never met Krajnyak but Beal spoke about visiting, going to dinner and taking trips with her.

The neighbor says Beal's wife had died and he seemed to be happy to have found someone to connect with.

Beal's son, Nathan, says his father and Krajnyak had recently broken up.

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10:50 a.m.

The brother of a woman who was killed when an explosion rocked a California medical office building says she had just left her native Hungary days before the blast.

Laszlo Krajnyak (KRY-nyak) told The Associated Press on Thursday that his younger sister had left family members in Tiszaujvaros on Monday. The blast occurred Tuesday.

His sister, 48-year-old Ildiko Krajnyak (IL-di-koh KRY-nyak), was a cosmetologist who ran a day spa in the building.

Nearly choking up at times, Laszlo Krajnyak said he had heard about the bombing on the news.

He said he had visited his sister for two weeks last month in order to help her with her business.

The son of a man arrested during an investigation of the explosion says his father had been in a relationship with Ildiko Krajnyak.

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10:20 a.m.

The son of a man arrested during an investigation into a deadly explosion in California says his father had been in a relationship with the woman killed in the blast but they recently broke up.

Nathan Beal told The Associated Press on Thursday that his father built sport rockets fueled by a propellant that is legally available at specialty hobby shops.

The FBI said Stephen Beal was arrested on suspicion of possession of an unregistered destructive device after a search of his Long Beach home. He has not been charged in connection with Tuesday's explosion in Aliso Viejo.

Nathan Beal says it seems highly unlikely that his father had a destructive device. He believes federal agents may have found "motor cases made out of aluminum."

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8:45 a.m.

A neighbor says the man arrested during an investigation into a deadly explosion in Southern California was often seen working on big rockets on his lawn.

The FBI said Thursday that Stephen Beal was arrested on suspicion of possession of an unregistered destructive device after a search of his Long Beach home.

He has not been charged in connection with Tuesday's explosion in Aliso Viejo.

Beal's Facebook page shows many photos of him apparently recently traveling with the woman who was killed, 48-year-old Ildiko Krajnyak (IL-di-koh KRY-nyak), a cosmetologist who ran a day spa at the building hit by the blast.

His neighbor, Stuart Davis, said he often saw Beal and his adult son working on large rockets on their front lawn.

He said the son told him they built movie props.

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6:30 a.m.

The FBI says the investigation into a deadly building explosion in Southern California has led to the arrest of a man on suspicion of possession of an unregistered destructive device.

FBI spokeswoman Laura Eimiller stresses in a statement Thursday that the subject, 59-year-old Stephen Beal of Long Beach, has not been charged in connection with Tuesday's explosion.

Beal's Facebook page shows many photos of him apparently recently traveling with the woman who was killed, 48-year-old Ildiko Krajnyak (IL-di-koh KRY-nyak), a cosmetologist who ran a day spa at the building hit by the blast.

Beal is expected to make an appearance in federal court Thursday afternoon.

Eimiller says no additional details will be provided until a federal criminal complaint is released.

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9:21 p.m.

Authorities are investigating whether a California woman killed in an explosion at the day spa that she owned was targeted.

Officials haven't formally identified the body but said Wednesday they believe it is that of Ildiko Krajnyak (IL-di-koh KRY-nyak), a licensed cosmetologist.

Investigators do not believe the Tuesday afternoon blast in the city of Aliso Viejo was an accident, and items that were possibly part of a bomb have been sent to an FBI lab. There have been no arrests.

Authorities declined to publicly say if they believe Krajnyak was the target, but one official briefed on the investigation told The Associated Press she had been the intended recipient of an explosive package.

Two injured people are expected to survive after surgery and a third was treated at the scene.