1.  Qualification.  Except as provided in subsection 2, a member qualifies for a disability retirement benefit if the member becomes disabled while in service and, for a member who by election remains covered under this section as written prior to its amendment by Public Law 1991, chapter 887, section 12, before normal retirement age.  

2.  Exception.  A member with fewer than 5 years of continuous creditable service preceding that member's last date of service is not eligible for a disability retirement benefit if the disability is the result of a physical or mental condition that existed before the member's membership in a retirement program of the Maine Public Employees Retirement System, unless the disability is a result of, or has been substantially aggravated by, an injury or accident received in the line of duty but from events or circumstances not usually encountered within the scope of the member's employment.