Bustamante is accused of sexually assaulting seven of his female co-workers while he was the director for Orange County Public Works. The 47-year-old is married with three children.
In court on Thursday, Bustamante pleaded not guilty to the charges. A pre-trial hearing date has been scheduled for Aug. 30.
Mauk was criticized for his handling of the allegations against Bustamante while he was a county employee. Following a meeting, the supervisors announced that Mauk agreed to resign effective Aug. 3.
The Board of Supervisors voted 4-1 to have the county's chief financial officer, Robert Franz, take over as acting CEO.