A founding member of a 1980s California-based experimental band was arrested Tuesday in connection to the slaying of his girlfriend who disappeared early last month.

Theobald "Theo" Lengyel, 54, who once performed with the band Mr. Bungle, was booked into the Santa Cruz County jail on a first-degree murder charge in connection to the suspected death of 61-year-old Alice "Alyx" Kamakaokalani, the Capitola Police Department reported.

Kamakaokalani, who lived in Capitola − a small, seaside town in Santa Cruz −was last seen on Dec. 3, 2023, prompting a missing person investigation nine days later, police Chief Andrew Dally told USA TODAY Wednesday.

Dally said his agency, with assistance from the Santa Cruz County Sheriff’s Office, arrested Lengyel Tuesday after an investigation led detectives in a wooded area within Tilden Regional Park in Berkeley where they discovered human remains.

Capitola is about 80 miles south of Berkeley, a city in Contra Costa County located in San Francisco's Bay Area.

Police did not say how the person died or where they believe they were killed, but said they believe the unidentified remains were Kamakaokalani's.

The identification of the human remains and their cause of death is pending DNA confirmation from the Contra County Coroner’s Office, police reported.

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'It became clear foul play was involved'

It was not immediately known who reported her missing but Capitola police, in conjunction with the El Cerrito Police Department, initiated an investigation into her disappearance on Dec. 12

Following a weeks-long investigation, "it became clear that foul play was involved, leading to the identification" of Lengyel as a suspect, Dally said.

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Motive not immediately known

Dally did not elaborate and police have not released a motive in the killing.

Santa County Sheriff's Office records show Lengyel remained jailed without bond on Wednesday.

It was not immediately known if he had obtained an attorney.

Police said the case remained open and under investigation.

Natalie Neysa Alund is a senior reporter for USA TODAY. Reach her at [email protected] and follow her on X @nataliealund.