Colleague working two jobs and committed fraud in ours

So I have a colleague who has like 8 YOE. He is working at a seed stage startup where I also work. We have a very lean team.

He joined a big MNC back in December but continued to work with us alongside. I got to know in February that he's working two jobs. I didn't share it with the team because he was leaving by mid April types.

Owing to closing FY, I started noticing weird things where the database was manually altered. After a lot of investigation, I found that this colleague was messing with DB and making him small amounts of money since 2022. 4 months after he joined us!

Our founders still don't know about his working at the other company. Not sure if I should share it with the founders now. He got fired yesterday for financial fraud from our company.