Section 5K. (1) A civil action pursuant to sections 5B to 5O, inclusive, for a violation of section 5B may not be brought (i) more than six years after the date on which the violation occurred; or (ii) more than three years after the date when facts material to the right of action are known or reasonably should have been known by the official within the office of the attorney general charged with responsibility to act in the circumstances, but in no event more than ten years after the date on which the violation is committed, whichever occurs last. A civil action pursuant to sections 5B to 5O, inclusive, may be brought for acts or omissions that occurred prior to the effective date of this section, subject to the limitations period set forth in this section.

(2) If the attorney general elects to intervene and proceed with an action brought pursuant to sections 5B to 5O, inclusive, for a violation of section 5B, the attorney general may file a complaint or amend the complaint of a person who has brought an action pursuant to said sections 5B to 5O, inclusive, to clarify or add detail to the claims in which the attorney general is intervening and to add any additional claims with respect to which the commonwealth or a political subdivision thereof contends it is entitled to relief. For statute of limitations purposes, any such pleading shall relate back to the filing date of the complaint of the person who originally-brought the action, to the extent that the claim of the attorney general arises out of the conduct, transactions or occurrences set forth, or attempted to be set forth, in the prior complaint of that person.

(3) Notwithstanding any other general or special law, rule of procedure or rule of evidence to the contrary, a final judgment rendered in favor of the commonwealth in a criminal proceeding charging fraud or false statements, whether upon a verdict after trial or upon a plea of guilty or nolo contendere, shall estop the defendant from denying the essential elements of the offense in any action which involves the same act, transaction or occurrence as in the criminal proceedings and which is brought under section 5B.