Police are investigating why someone buried a car in the yard of a multimillion-dollar northern California home in the 1990s – and left unused bags of concrete inside. The car was discovered on Thursday morning by landscapers in the affluent town of Atherton in Silicon Valley, police said in a news release. Cadaver dogs alerted to possible human remains but more than 12 hours after the car was recovered none had been found, Atherton police commander Daniel Larsen said. “The cadaver dogs made a slight notification of possible human remains. The San Mateo crime lab was contacted and sent technicians to assist with excavating the vehicle. Excavation is ongoing and at this time, no human remains have been located,” police said. Police believe the car was buried 4ft to 5ft deep in the 1990s. Larsen would not say what led detectives to that conclusion. The bags of concrete were placed throughout the vehicle, which was blanketed by dirt over the roof, Larsen said. According to an NBC Bay Area anchor, Gia Bang, police said the car was a Mercedes. The sprawling home and property is valued at $15m, the San Francisco Chronicle reported. According to the outlet, the property includes a 12,000 sq-ft home purchased by the current owners in 2020. Zillow records indicated that the home, built in 1990, was listed for rent in 2013 and 2014. Larsen said police believed the car was buried before the current homeowners bought the home, and that they were not under investigation. “The motive and circumstances surrounding this incident are under investigation,” police said. Atherton is one of the wealthiest towns in the US, with about 7,000 residents in nearly five square miles. The discovery has baffled some resident. One, Athena Ogawa, told NBC Bay Area: “It’s a mystery in my own neighborhood.” Another resident, Peter Sun, said: “It’s kind of strange. But usually, it’s pretty safe and it’s like everyone is kind of doing their own thing.”