Kickbacks - Construction

Ok, so I do subcontracts for a construction firm.

Recently a Project Manager pissed off a subcontractor so bad that the Subcontractor emailed me and 3 other people proof of kickbacks. Apparently, this PM had his kickbacks paid to him via Zelle and the Zelle account is 100% in the PM's name, all round numbers, all line up with when the sub was awarded subcontracts.

The owner of the company's response was horrible. Said "its not really that much money", "I'm sure other people do it too", and didn't say anything when I asked "are you going to at least put the PM on administrative leave?".

The PM is still working (Only a few days now).

I've told the owner I am no longer doing anything for this PM. Its one thing to suspect a PM of doing it, its another to be presented with evidence of him taking kickbacks and choosing to do nothing.

My questions are:

1. Is the company now liable/culpable (I don't know what the term is) for allowing a workplace to take kickbacks from subs?
2. One of the other people on the email was accounts payable, would she be in trouble knowing this info and still writing checks?
3. Since I put in writing my refusal to work with this PM and his Boss (that not only allows this but encourages it) am I clear?