
Quoting
4eyedbuzzard
I think if I were you I would start writing down a list of witnesses that could possibly testify that you were performing the company's business during the time he alleges you forged the checks. People that that saw you there: other employees, contractors, USPS, UPS, FedEx, other delivery people, etc; people you contacted such as A/P and A/C, suppliers, cutomers, etc; any documents such as signing for certified mail or deliveries(they keep records) - in short anything that would show or anybody that could testify that you were working for him/doing the company's business at the time he alleges you forged the checks. Also get any phone records or correspondence that might prove you were in contact with him during this period. Since you might well know the inside workings of his business as well, keep in the back of your mind any other other potentially usful information such as how well he complied with IRS reporting especially the timely filing of 941's and state reporting requirements for taxes, UI, WC, etc, etc.
Then I'd go talk to a lawyer and explore my options.