I. Except as provided in paragraph II, no actions shall be maintained against the governmental unit under this chapter unless the same is commenced within 3 years after the time of injury or damage, except that when the injury and its causal relationship to the act or omission were not discovered and could not reasonably have been discovered at the time of the act or omission, the action shall be commenced within 3 years of the time the plaintiff discovers, or in the exercise of reasonable diligence should have discovered, the injury and its causal relationship to the act or omission complained of. As a condition precedent to commencement of the action, the clerk of the governmental unit shall be notified by registered mail within 60 days after the time of the injury or damage or discovery of the injury or damage, if it could not reasonably have been discovered at the time of the occurrence of the injury or damage, as to the date, time and location where the injury or damage occurred, and provided that in any case where lack of written notice, actual knowledge or reasonable opportunity to obtain knowledge of any injury or damage within the 60-day period is alleged by the governmental unit, the burden of proof shall be on the governmental unit to show that it was substantially prejudiced thereby.
II. A person, alleging to have been subjected to any offense under N.H. Rev. Stat. Chapter 632-A or an offense under N.H. Rev. Stat. § 639:2 by a governmental unit, may commence an action at any time after the injury or damage occurs. The requirement for notification to the clerk of the governmental unit shall not apply to an action based on an offense under N.H. Rev. Stat. Chapter 632-A or N.H. Rev. Stat. § 639:2.