Authorities search a car that may have been buried for decades in Atherton, California.
CNN  — 

Authorities investigating the mystery surrounding a vehicle buried on a residential property near San Francisco said no humain remains were found at the scene, a day after cadaver dogs had indicated their presence in the area.

The vehicle buried in the backyard of a home in Atherton, California, was first spotted Thursday morning by landscapers working on a project for the current homeowner, police said.

“Due to the unknown nature of why the vehicle was buried, cadaver dogs were called to the scene,” Atherton police said Thursday in a news release. “The cadaver dogs made a slight notification of possible human remains.”

A cadaver dog again gave a “slight notification of possible human remains” on Friday, Police Chief Steven McCulley said in a Monday news release.

But a Sunday examination with ground penetrating radar “did not reveal anything unusual or suspicious at the scene and no human remains were located. This concluded our on-scene investigation,” McCulley said. “The motive and circumstances surrounding this incident continue to be under investigation.”

Police Cmdr. Dan Larsen previously said the dogs’ indication could also be due to the presence of blood, old bones or vomit – landscapers have been on site, and if anyone bled or vomited, the dog could be reacting to that.

A car was found buried in the backyard of a home in Atherton, California.

San Mateo Crime Lab technicians began excavating the vehicle on Thursday, police said, and it was removed from the property and taken to the crime lab on Saturday.

It appears the vehicle, a convertible Mercedes-Benz that was reported missing in 1992, was buried about 4 to 5 feet underground, Atherton Mayor Rick DeGolia said. The car was found with the top down and bags of concrete pieces throughout, including in the trunk.

Police have identified a possible owner of the vehicle and are attempting to verify through motor vehicle records, but it appears the owner has since died, the mayor said. Police would not say how the owner died as they are still working through the verification process.

The motive and circumstances surrounding the burial of the car are under further investigation.