According to interim Police Chief Leon Krolikowski, Bender alerted him to his decision about two weeks ago.
"He did not give a reason specifically, just that it's his time and ready to go. We wish him well," Krolikowski said Thursday morning.
Bender has been on vacation since July 19, and when reached by email, he was not immediately able to comment.
The move follows the retirement of Chief Ed Nadriczny, who left in June. Krolikowski, then a captain, moved up to take his place as interim chief until a replacement is found. The Police Commission and a talent search firm are in the process of finding a new chief.
Police Commission Chairman Jim Cole did not immediately respond for comment.
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