The owner of a Washington state auto glass installation business has admitted to overbilling Farmers Insurance Co. by at least $100,000 over the last several years.

Robert T. Wooster, 51, of Battle Ground, Wash., who operates Dr. Bob’s Auto Glass and DRB Enterprises Auto Glass, pleaded guilty in Clark County Superior Court to the felony charge of first-degree theft, according to the Washington State Office of the Insurance Commissioner.

Wooster is believed to have overcharged Farmers by at least $100,000 and perhaps significantly more, according to the office.

Farmers contacted Washington insurance regulators, who served a search warrant on Wooster’s businesses in late 2007, seizing dozens of fraudulent invoices.

The office’s Special Investigations Unit found that Wooster had a pair of schemes for illegally billing the insurer. Through one scheme, he would replace chipped or cracked windshields, but bill Farmers for more expensive side or back windows in more than 100 cases.

Wooster also allegedly submitted bogus invoices, cutting and pasting photocopied dealer invoices to make it appear like his costs for the glass were much higher than they really were. He also fabricated false invoices for parts that were never really installed, such as new window moldings, according to the insurance office.

He is scheduled for sentencing in mid-February 2010.