1. A member in active service who becomes totally and permanently disabled, as defined in this section, shall be entitled to retire and to receive a base pension determined in accordance with the terms of this section. Members who are eligible and totally and permanently disabled shall receive a disability pension computed as follows:

(1) Duty disability, fifty percent of final compensation as of the date of disability;

(2) Nonduty disability, thirty percent of final compensation as of the date of disability, provided that a nonduty disability pension shall not be available to any member with less than ten years creditable service;

(3) In no event shall the disability pension be less than the amount to which the member would be entitled as a pension if the member retired on the same date with equivalent age and creditable service.

2. For purposes of sections 86.1310 to 86.1640, the following terms shall mean:

(1) “Duty disability”, total and permanent disability directly due to and caused by actual performance of employment with the police department;

(2) “Nonduty disability”, total and permanent disability arising from any other cause than duty disability;

(3) “Total and permanent disability”, a state or condition which presumably prevents for the rest of a member’s life the member’s engaging in any occupation or performing any work for remuneration or profit. Such disability, whether duty or nonduty, must not have been caused by the member’s own negligence or willful self-infliction.

3. The retirement board in its sole judgment shall determine whether the status of total and permanent disability exists. Its determination shall be binding and conclusive. The retirement board shall rely upon the findings of a medical board of three physicians, and shall procure the written recommendation of at least one member thereof in each case considered by the retirement board. The medical board shall be appointed by the retirement board and expense for such examinations as are required shall be paid from funds of the retirement system.

4. From time to time, the retirement board shall have the right to require proof of continuing disability which may include further examination by the medical board. Should the retirement board determine that disability no longer exists, it shall terminate the disability pension. A member who immediately returns to work with the police department shall again earn creditable service beginning on the first day of such return. Creditable service prior to disability retirement shall be reinstated. A member who does not return to work with the police department shall be deemed to have terminated employment at the time disability retirement commenced; but in calculating any benefits due upon such presumption, the retirement system shall receive credit for all amounts paid such member during the period of disability, except that such member shall not be obligated in any event to repay to the retirement system any amounts properly paid during such period of disability.