ANTIOCH -- A state investigation recently uncovered what a commander called the "most egregious case" of falsifying odometer readings by a used car dealership that he has ever seen, officials said Tuesday.

Jorge's California Car Sales is suspected of rolling back the odometers on nearly half the cars on its lot, said Area Cmdr. Tom Wilson of the California Department of Motor Vehicles. The alleged crime was discovered, he said, after a woman bought a car from the dealership earlier this year, immediately began having problems with it and filed a consumer complaint.

"I've been doing this 14 years, and in that time, this is the most egregious case we've ever been involved with in regards to a dealership," Wilson said. "We're still trying to find victims, because we know there are a lot more out there."

The months-long investigation led to the June 11 arrest of lot owner Jose Guevara on suspicion of grand theft, attempted grand theft and odometer tampering.

Wilson said that at one point of the investigation, 23 of 47 cars on the lot were found to have faulty odometer readings.

The lot was open for business as usual Tuesday, but a call left for the store's owner was not immediately returned.

Wilson said the investigation began after a woman bought a car at the lot that was said to have around 100,000 miles on it. But "within a couple weeks," Wilson said, the engine blew up, capping a long list of issues. As she investigated and sought relief, Guevara refused to help her, Wilson added.

Guevara is accused of buying the cars for his lot at auctions throughout the state, Wilson said. Through online technological tools sold on the Internet, Wilson said Guevara was able to roll back the computerized odometers and have the cars on the lot within a couple of days. Investigators believe the scam was executed in a smog shop at the Guevara Inc. dealership, Wilson said.

The scam has been a problem in the state's Central Valley for years, Wilson said, but is becoming more prevalent in Northern California.

"Anytime, you're going to buy a used car, the law states you have the right to bring it to an individual mechanic, at your cost, to have it checked out before the deal is complete," Wilson said. "If you tell a dealership you want to do that, and they tell you that's against their policy, that's a tip-off that you shouldn't be buying a car from that dealer."

Wilson also advised used car buyers to do research on vehicles by entering vehicle identification numbers into Google and seeing what information is available.

"The more research you can do on your own, the less likely you're going to be a victim," he said. "The consumer has to be wary."

Contact Rick Hurd at 925-945-4789 and follow him at Twitter.com/3rderh.