Sec. 4.01. MEMBERSHIP IN FUND; ELIGIBILITY. (a) A person who has been properly appointed and enrolled as a police officer in a municipality adopting this Act automatically becomes a member of the pension fund of the municipality on the 91st day after the date the municipality adopts the fund created by this Act, except as provided under Section 11.01 of this Act. A person who is already a member of and contributor to a municipality's police pension fund retains and is entitled to all rights and privileges due the person by virtue of having been such a member and contributor.

(b) A person who is not a member of the pension fund on the date for automatic membership under Subsection (a) of this section and who becomes properly appointed and enrolled as a police officer of a municipality adopting the fund created by this Act automatically becomes a member of the fund as a condition of the person's employment, except as provided under Section 11.01 of this Act.

(c) A part-time police officer, a temporary police officer performing emergency services, or a police officer compensated on a fee basis is not eligible for membership in the pension fund.