(a) Investigations under this Rule 5 may be initiated only within five years after the Chief Disciplinary Counsel knows or should know of the alleged acts of misconduct. If the investigation involves a course of alleged misconduct, the time of limitation shall date from the last act of alleged misconduct. Investigations relating to a felony, requests for reciprocal discipline under Rule 5.20, and requests for discipline under Rule 5.21 are not subject to any time limitation.

(b) The limitation period is tolled during any time tolling would be allowed in law, including the period:

(1) The lawyer actively conceals the professional misconduct;

(2) The complainant has not attained the age of 18 years; or

(3) The complainant is incapacitated.