In September, Mueller filed a suit against Swift claiming he was fired by his job and banned from the star's concerts based on false allegations he groped her before her concert at the Pepsi Center in June of 2013, reported People magazine.
As per the counter suit obtained, Mueller, who was previously terminated twice from on-air radio jobs at other stations and had not worked as an on-air personality since May 2006, according to the papers admitted Swift was assaulted but blamed "his superior" at KYGO, Eddie Haskell.
"Resolution of this Counterclaim will demonstrate that Mueller alone was the perpetrator of the humiliating and wrongful conduct targeted against Ms Swift, and will serve as an example to other women who may resist publicly reliving similar outrageous and humiliating acts."
The papers allege Mueller and his girlfriend were participating in a meet-and-greet with Swift, 25, when he "intentionally reached under her skirt, and groped with his hand an intimate part of her body in an inappropriate manner, against her will, and without her permission."
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Swift was "surprised, upset, offended, and alarmed," and informed her photographer, tour manager and security team, according to the papers.
According to the suit, Swift, who is demanding a jury trial, will be donating any money she wins from the suit to "charitable organisations dedicated to protecting women from similar acts of sexual assault and personal disregard."
Neither Swift's representative nor Mueller's lawyer could be immediately reached for comment.