Can I be liable for witnessing proxy job interview fraud?

A person I know is running a U.S.-based consultancy company from India, which conducts proxy or fraudulent job interviews. He provides voice support in the background for candidates who are physically in the U.S. on a visa. If the candidate is selected, they pay a portion of their salary to him as commission. Although I don’t have concrete evidence, I have seen him providing voice support during interviews. I’m concerned—could I face any legal consequences, or be questioned by the police or court about my involvement or knowledge? There are others who also know about this. Where and how can I report this, and which agencies should I contact?