Prosecutors said Monday a former Santa Rosa grocery store cashier stole $142,000 from G&G Supermarkets in the latest embezzlement to surface in Sonoma County.

Steven Lau, 56, of Forestville is accused of pocketing up to $3,000 a month from the family-owned grocery chain over a three-year period ending in January.

The longtime employee is suspected of covering it up by altering transaction records, prosecutor Amy Ariyoshi said. It went undetected for so long because no one believed Lau would steal from the company, Ariyoshi said.

"It's the same in all these cases," Ariyoshi said. "He was a trusted employee."

Teejay Lowe, chief executive officer of G&G Supermarkets, declined to discuss the case or say how long Lau had been an employee, citing an ongoing investigation. He said only that Lau was not a relative.

Lau came under suspicion when a customer tried to return a piece of meat and the receipt didn't match up, Ariyoshi said.

An investigation revealed unusual cash register activity connected to Lau, she said. He appeared to be cancelling a high number of cash transactions or marking them as returns, dating as far back as January 2010, she said.

Police looked deeper and found he was taking the money for himself, she said. The theft was confirmed by store surveillance cameras, which captured Lau making notes about transactions and fudging receipts, Ariyoshi said.

Lau made large bank deposits and appeared to be spending money on home repairs, she said.

He was confronted by store managers earlier this year and fired. Lau was arrested May 29 and charged with four felonies, including grand theft with white-collar crime enhancements and possession of more than $400 in stolen property.

He is free on $20,000 bail and is expected to enter a plea July 11. He faces more than five years in prison if convicted.

Lau's lawyer, Richard Scott, said it was too early to comment on the case.

"We are reviewing the allegations," he said.

The charges are the latest in a string of embezzlements to strike local businesses, churches, schools or youth organizations. Over the last three years, 14 Sonoma County residents have been accused of stealing $5.7 million from their employers or community groups they led.

Late last month, a former Healdsburg soccer league president, Mitzi Giron, 30, was charged with using the organization's ATM card to steal more than $51,000 over an 18-month span. Her predecessor, Kyle Hoffman, 38, was sentenced to nine months in jail for embezzling $58,000 from the club.

Former Santa Rosa Junior College police officer Jeff Holzworth, 51, was charged last year with stealing $287,000 from campus parking meters over eight years. A preliminary hearing is scheduled in August.

In November, John C. Sheehan of Rohnert Park was sentenced to nine years in prison for embezzling $1.2 million from his employer, Petaluma-based Bibbero Systems Inc.