My boss often has one of my co-workers Photoshop new dates, prices, addresses, and even names onto invoices in order to fraudulently submit them for rebates. My boss and co-worker are very open about this, and everyone in the company (~10 people) knows that it's something they do.
I have tried to bring up the issue with my boss in the past, but have always been met with: "How are they going to find out?" and "I don't want you to worry about this"
I want to, in the very least, be able to advise my co-worker that there's a chance he could get into legal trouble if the company they were submitting the rebates to found out.
What can I do to protect my self and my coworker from repercussions?
Edit: A quick google search reveals that the laws in my jurisdiction classify the forgery as a fifth degree felony (USA) and that also failure to report any crime (except in certain situations) is a fourth degree misdemeanor.
Reporting something like this would lead to me being immediately fired.