Your employers is not supposed to retaliate against you or terminate you because you spoke to OSHA. Congress put an anti-retaliation provision in OSHA, so employees can be free to report dangerous conditions without retaliation. You should contact an attorney or OSHA and file a claim for retaliation if your employer takes any action against you.
This is not intended to be legal advice, but is only for general information. Cantact an attorney in your area for legal advice.
it is protected activity to participate in an OSHA investigation. I recommend that you contact OSHA, and that you advise the OSHA investigation specifically of what you know and dont know to set the record straight.