Tell him you know what's up, that you are giving him two weeks to reimburse the company in full and not a penny less, and that if he does that, this will be for

Tell him you know what's up, that you are giving him two weeks to reimburse the company in full and not a penny less, and that if he does that, this will be forgiven this one time. Make it clear that anything except 100% compliance and it's straight to the lawyers / police. No bargaining. The company is likely screwed anyway if one of the founders can't be trusted at all.