The board approved a shortlist search in June, according to recently released minutes of the Sept. 25 board meeting.
Separately, the pension fund lowered its assumed rate of return to 7.5% from 7.75%.
The board also lowered its inflation assumption to 3.5% from 4%. The reductions followed a presentation by The Segal Co., the $2.2 billion pension fund's actuarial consultant.
Matthew O'Reilly, chief investment officer, did not return a telephone call seeking more information by press time.