A former disc jockey who was fired from a radio station in Denver after Taylor Swift alleged that he groped her is firing back in court, saying her story “defies credibility.”

David Mueller was fired from KYGO after an alleged incident backstage at a Swift performance at the Pepsi Center in Denver in 2013. The superstar alleges that Mueller reached up her skirt and touched her inappropriately while taking a photo during a meet-and-greet. KYGO dismissed the disc jockey after Swift’s management brought up the subject to station management.

Billboard reports that Mueller and his legal team have filed a response to Swift’s request for summary judgment in an ongoing lawsuit over the incident, ridiculing her claim by writing, “The contention that Mr. Mueller lifted up Ms. Swift’s skirt and grabbed her bare ass (while standing with his girlfriend, in front of Ms. Swift’s photographer and other staff, as well as Ms. Swift’s highly trained security personnel, during an employer sponsored, VIP, backstage meet and greet) defies credibility.”

Mueller first filed a lawsuit against Swift in 2015, alleging slander and interference with his employment contract, and Swift fired back with a countersuit claiming assault and battery. Swift gave her side of the alleged incident in a deposition in July.

“Right as the moment came for us to pose for the photo, he took his hand and put it up my dress and grabbed onto my ass cheek and no matter how much I scooted over it was still there,” Swift said, according to Billboard . “A meet and greet is supposed to be a situation where you’re thanking people for coming, you’re supposed to be welcoming people into your home, which is the arena for that day, and for someone to violate that hospitality in that way, I was completely stunned.”

On Oct. 21, a judge agreed to seal a photo from the meet-and-greet that Swift says supports her claim of assault. The photo will remain sealed until the case goes to trial.