Iowa Code § 410.13
The board of trustees of each department shall have power, at any time, to cause any member of such department retired by reason of physical or mental disability to be brought before it and again examined by three competent physicians appointed by the board of trustees to discover whether such disability yet continues and can be improved and whether such retired member should be continued on the pension roll, and shall have power to examine witnesses for the same purpose. The question of continued disability or ability to perform regular or light duty in the police or fire department shall be determined by the concurring report of at least two of the three examining physicians. Such member shall be entitled to reasonable notice that such examination will be made, and to be present at the time of the taking of any testimony, shall have the right to examine the witnesses brought before the board and to introduce evidence in the member's own behalf. All witnesses shall be examined under oath, which may be administered by any member of such board.
Iowa Code § 410.13