A California man was arrested Sunday in connection with an explosion that killed his ex-girlfriend at her day spa in May 2018, officials said.

Stephen Beal, 59, of Long Beach, was taken into custody, FBI spokeswoman Laura Eimiller said. She declined to detail the new charges but said more information would come in a Monday news conference.

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Beal had originally been arrested on suspicion of possessing explosives after the bombing last year. However, prosecutors dropped the charge after questions arose about whether material that was discovered in Beal’s home qualified as a “destructive device.” Authorities at the time found two improvised explosive devices, three firearms and more than 100 pounds of explosive material.

Beal wasn’t named a suspect after the charge was dropped.

The May 15 bombing killed Ildiko Krajnyak, 48, in her Aliso Viejo spa. Two female clients were also seriously injured after Krajnyak opened a box that erupted in a fiery explosion at the spa, investigators said. She had just returned to California, after visiting her family in Hungary, when she was killed.

Beal initially told investigators that he and Krajnyak had recently broken up over issues of exclusivity and finances, according to an affidavit filed by an FBI agent. The two had remained business partners, however.

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Beal, a model-rocket hobbyist, also told investigators he had not made any bombs and did not have material for an explosion like the one he saw in news coverage.

The Associated Press contributed to this report.