Police in California are investigating a home’s backyard after its owners dug up a skull and bones during a renovation project.

The gruesome discovery was made on Sunday in Santa Ana, and it’s unclear whether the remains are male or female, KTLA reports.

Police say the home burned down in 2006 and has since been rebuilt. The former owner, who neighbors described as a hoarder, is now being questioned by detectives.

“We’re also looking at any missing people during that time period,” Santa Ana Police Cpl. Anthony Bertagna told KTLA.

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