(1) Upon retirement for disability, as hereinabove provided: PROVIDED, The disability is not due to intemperance, willful misconduct or violation of law, of which the board shall be the judge, a member shall receive a retirement allowance which shall consist of:

(a) An annuity which shall be the actuarial equivalent of his or her accumulated contributions at the time of his or her retirement.

(b) A pension purchased by the contributions of the city, which, together with his or her annuity provided by his or her accumulated normal contributions, shall make the retirement allowance, exclusive of the annuity provided by his or her additional contributions equal to (i) one and one-fourth percent of his or her final compensation multiplied by the number of years of service which would be creditable to him or her were his or her services to continue until attainment by him or her of age sixty-two. The minimum disability retirement allowance shall be nine hundred sixty dollars per year.

(2) If disability is due to intemperance, willful misconduct or violation of law on the part of the member, the board of administration in its discretion may pay to said member in one lump sum, his or her accumulated contributions, in lieu of a retirement allowance, and such payment shall constitute full satisfaction of all obligations of the city to such member, and upon receipt of such payment he or she shall cease to be a member of the retirement system.

(3) Upon the death of a member while in receipt of a disability retirement allowance, his or her accumulated contributions, as they were at the date of his or her retirement, less any annuity payments made to him or her, shall be paid to his or her estate, or to such persons having an insurable interest in his or her life as he or she shall have nominated by written designation duly executed and filed with the board.