The applicable law and corresponding statute of limitations depends upon the type of fraud being committed, and who is committing it. One law commonly used to prosecute Section 8 fraud is the Federal False Claims Act, which has a 6 year statute of limitations (31 U.S.C. Section 3731(b)(1)).
The Federal False Claims Act, also known as the "Lincoln Law," is a law that imposes liability and penalties upon people or companies that knowingly submit a false or fraudulent claim for payment or approval to a government entity (31 U.S.C. §§ 3729–3733). Depending upon the facts of the situation, a fraudulent Section 8 Claim may qualify as a violation of the False Claims Act. Penalties for violation of the FCA are a fine of $5,000 to $10,000 plus three times the amount of damages the government sustains as a result of the fraud.
In addition to the Federal False Claims Act, many states have corresponding False Claims Acts written into their law. Depending on your location, there may be an applicable state statute, and the state statute may have a different statute of limitations. It may be advisable to consult an attorney regarding your rights and duties.