Whats th worst that can be done?

I used to work at a computer shop, i was 18 when i started working. I was working under the books if thats the correct term. So i guess i never officially worked there. I stopped going after a a few months, was tired of my boss's crap and working conditions. I'm being accused of selling a laptop to someone. (A laptop that was put for trash). Which i didnt for the record, and even if i did, it was trash. That shop is illegal all around, they burn windows installation discs, and reuse cracked serial keys, and distribute them. Even cracked microsoft office software. They've been doing it for years. I believe the reason he is accusing me of this, is because I left the job and i was his only/best employee. Theres been times he hasnt even payed me. The person is claiming i sold them a computer, they're bringing it back saying it has problems, they have no receipt, or anything. I think he either hired them, or they're just trying to get free repairs. he is talking about cops. How can this turn out? Basically they're words against mine.