(a) No credit shall be given for service rendered after April 1, 1989, by a member who is also a member of the Peace Officers' Annuity and Benefit Fund if such service is creditable under the Peace Officers' Annuity and Benefit Fund to which such member belongs.

(b)(1) Any member who first became a member of the fund on or after July 1, 1993, and who is also a member of the Peace Officers' Annuity and Benefit Fund shall not be eligible for creditable service in the fund for any period after that date with respect to which such member is also entitled to any creditable service in the Peace Officers' Annuity and Benefit Fund.

(2) Any person who was a member of the fund on July 1, 1993, and who subsequent to that date was placed on a leave of absence from the fund by action of the board of trustees and who from that date to July 1, 1996, was continuously employed as a firefighter or who was continuously enrolled as a volunteer firefighter may, upon again becoming a regular, active member of the fund, obtain creditable service for 36 months of service by paying the regular dues which would have been made for each month of service if such leave of absence had not been imposed, provided that such member otherwise satisfied the requirements for creditable service during such period. Such payment must be made to the board of trustees not later than December 31, 1996.