What is the statute of limitations for an individual to sue a public company, after learning that his expert witness was tampered with, and now CONFIRMED by the L.A. D.A.'s office, whether in California court or Federal court?
If the case is still pending you would need to file motions in that court/case. If the case ended there is a limited amount of time in which to seek a new trial based on new evidence or to have a judgment overturned. It depends on the court. If you want to sue for damages based on an adverse judgment obtained in another case you can start a new suit on those grounds but the applicable statute of limitations on that would depend on the nature of the cause of action/claim. You should consult with an attorney.
Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.