"I want people to have a good time at my meet-and-greets at concerts", she said.
"No, I am critical of your client for sticking his hand under my skirt and grabbing my bare ass", she replied, as reported by CNN.
Swift also answered questions related to her body guard at the time, Gregory Dent - like why he didn't take action after noticing Swift was uncomfortable following her interaction with Mueller. He stayed latched on to my bare ass cheek as I lurched away from him.
"I'm not going to allow you or your client to make me feel in anyway that this is my fault because it isn't", the singer continued, before saying, "I am being blamed for the unfortunate events of his life that are a product of his decisions and not mine".
"It made me, as a parent, question why I taught her to be so polite", she said.
Mueller initiated the litigation, claiming Swift fabricated the story and put pressure on KYGO to fire him from his $US150,000 ($191,000) -a-year job.
Swift, one of the most popular performers in the U.S. music business, spoke forcefully as she described the incident with Mueller.
"It was just destroying her", the elder Swift testified.
She says she is not suing for money, but rather to convey a warning on behalf of all American women about sexual assault, and is hoping that a favorable verdict by a Denver jury of six women and two men will send the message of "get your groping hands off us" to men across the nation and around the world.
Robert Call, general manager of the radio station Mueller worked at, confirmed the DJ was sacked for the incident.
Her testimony lasted about an hour. Each side of the trial has attempted to use the photo to bolster their argument, but Swift rejected McFarland's claim that the photo showed nothing inappropriate.
On Wednesday the court heard from Mueller, Swift's mother and Bell.
She testified that Swift later told her what happened, looked at a photo and pointed out Mueller as the person responsible. According to her lawyer, it depicts a grin on Mueller's face and the positioning of his hand directly behind her buttocks, clearly suggestive of an improper and humiliating touching. "I know that it happened".
Swift testified Mueller grabbed her behind underneath her skirt, not above it, during the pre-concert meet-and-greet photo session. She said she told him and his girlfriend, who was also in the photo, "thank you for coming" in a monotone voice before they left.
Call said he fired the DJ because of his shifting accounts of the incident, and because the photo showed that Mueller's hand was "not where it was supposed to be". Swift said the incident was unexpected, as well as unprecedented.
Mueller maintains that he didn't grope Swift, and has alleged that someone else at the meet-and-greet may have.
David Mueller is a former radio show host. Yet four years later, Swift and former DJ David Mueller are embroiled in a widely publicized federal court case. Whatever the truth of Swift's situation, most who are assaulted don't speak up.
He sued the 10-time Grammy victor two years after the incident - but says he's not asking for the $3 million advised by a damages expert.
On Wednesday, Andrea Swift delivered dramatic testimony as she described learning about the alleged groping of her daughter.
Swift countersued, claiming sexual assault.
Mueller has his right hand concealed behind her rear end, and Swift appears to have shifted her hip slightly away from him. And it's a statement she can't make enough, especially if it inspires just a single victim of assault to say it herself.