The Riddler's worst moment is also his first: Brutally killing the mayor of Gotham City, Don Mitchell Jr., on Halloween night. It's a brazen way to kick off his vicious campaign, and he couldn't have done it in a more cold-blooded way.
Shortly after watching news coverage of Mitchell's mayoral debate with Bella Reál, the Riddler sneaks into his home and viciously beats him to death. He leaves Mitchell's body propped up on a chair with his head wrapped in duct tape, with the words "NO MORE LIES" scrawled across his face. To add to the gruesomeness of this crime, Mitchell's thumb is removed and later found attached to a USB drive in his car, giving horrible new meaning to the phrase "thumb drive." It includes photos of Mitchell with another woman, Annika, confirming he was having an affair. Following this discovery, the photos are leaked to the media.
What makes this act the Riddler's worst moment is that it doesn't end with the mayor's murder. From cutting off his thumb to ruining his reputation after his death, this is all part of the Riddler's larger plan to reveal just how vile those who run Gotham City really are — according to the Riddler, anyway. While Mitchell is no saint, like so many of the Riddler's other victims, he's still a husband and father. Thanks to the Riddler's cruelty, his wife and child don't just lose him — they lose their unsoiled memories.
