When sheriff's deputies in Southern California raided a suspected drug house they found the expected - guns and methamphetamine. But something else, too: Some two dozen granite tombstones in the backyard.

The stones turned up at a home in Loma Linda Tuesday, San Bernardino County sheriff's spokeswoman Jodi Miller told Reuters.

The tombstones had custom inscriptions on them and several of them were traced to the nearby community of Colton. Investigators found garden tools, including shovels, in the yard. Authorities believe the residents of the home dug out the tombstones but are at a loss to say why.

Authorities valued the grave markers at about $48,000, but their resale value is probably minimal.

"We're all trying to figure out why. There's no monetary value to these. They are made out of stone, so they are very, very heavy," said Miller.

The gravestones had small amounts of metal and brass attached but there was no indication that thieves were stealing them for those materials, added Miller.

Deputies also found two firearms and evidence that the residents were selling methamphetamine at the house.

The police arrested John Bleuer, 50, during the search on charges of methamphetamine possession and sales, possession of firearms and possession of stolen property. Deputies are looking for three other suspects.