David Mueller, who was fired from his job at KYGO-FM, said earlier under oath that the photo of him and Swift appears "weird" and "awkward" but he vehemently denied that he inappropriately touched the pop star during a meet-and-greet.
The trial centers on Swift's allegation that Mueller reached under her skirt and grabbed her behind before a concert at Denver's Pepsi Center in June 2013.
Swift's team told KYGO, a CNN affiliate, about the incident, and Mueller, then 51, was fired two days later.
In 2015 he sued Swift, her mother, Andrea Swift, and her radio promotions director Frank Bell, alleging that they pressured KYGO to terminate him and that he lost his job because of a false accusation.
On Wednesday the court heard from Mueller, Swift's mother and Bell.
During emotional testimony, Andrea Swift gestured at Mueller and said, "He sexually assaulted her. Right there, that guy."
Mueller had testified that his and Swift's hands and arms touched as they got into position for the photo, which shows Taylor Swift with Mueller to her left and Mueller's then-girlfriend, Shannon Melcher, on her right.
Mueller said his hand was in a closed fist and touched what seemed to be her ribs, and he denied any groping or inappropriate contact on her rear end.
On cross-examination Wednesday, Swift's attorney, Doug Baldridge, questioned the positioning of Mueller's hands at the photo-op.
"I know my palm was facing down. I do know that, sir," Mueller said.
The photo, leaked last year and shown in court, shows Mueller with his hand hidden from view below Swift's lower back. Swift's attorneys have pointed to that as evidence of the inappropriate touching, and noted that KYGO cited the photo as one reason for his termination.
However, Gabriel McFarland, Mueller's attorney, said the photo did not show the inappropriate under-skirt touching that Swift has alleged.
"If you look at that photo, his hand is not underneath her skirt. It's not ruffled, rumpled, affected in any form or fashion," McFarland said.
Andrea Swift disagreed that the skirt was not affected. It was made of a stiff material, she said during cross-examination, and she thinks the photo shows it lifted up by Mueller's right arm.
"There's something going on in her eyes," Andrea Swift said of the photo. "The second I saw (the photo) I knew something was horribly wrong."
Swift, who was 23 at the time, has filed a countersuit in which she accused Mueller of "reaching under her dress and grabbing her bottom" as they posed for the photo.
Mother: Taylor said she was groped
Andrea Swift also told the court that her daughter was visibly upset after the incident.
"Mom, a guy just grabbed my (rear end) in the meet and greet," Andrea Swift said her daughter told her. She described her daughter as humiliated.
"I wanted to vomit and cry at the same time," Andrea Swift said.
During cross-examination the mother added that she couldn't believe Taylor thanked Mueller for being there.
"It made me, as a parent, question why I taught her to be so polite," she said.
Andrea Swift said she wanted Mueller to get fired but didn't demand it of his employers. She wanted to keep the photo and the incident private.
"I did not want this incident to define her life," she said. "I did not want her to have to live through the endless memes and gifs."
Bell, the final witness of the day, also wouldn't agree with McFarland's assertion that the photo doesn't show Mueller's hand up her skirt.
Bell said there was no way of telling, but Taylor Swift told him she was groped.
'I want to clear my name'
Mueller maintains that he didn't grope Swift, and has alleged that someone else at the meet-and-greet may have. He says that her accusation cost him his future in radio.
"It cost me my career. It cost me my income. It's been hard on my family. It's been hard on my friends," Mueller said.
"I want to clear my name," he added.
Mueller's suit doesn't seek a specific monetary amount, but an expert retained by the ex-radio host determined that nearly $3 million was a fair compensation for damages.
In cross-examination Tuesday, Mueller said that he had recorded a conversation he had with his KYGO bosses discussing the alleged touching. However, Mueller admitted that several of his electronic devices broke and that unedited versions of those recordings had been lost.
In addition, Baldridge referenced Mueller's description of Swift in a court deposition as cold and standoffish. Hearing that, Swift sat up in court, looking disgusted. She then wrote on a yellow Post-It note and passed it to one of her attorneys sitting across the table.
Mueller testified that he drew that conclusion because Swift didn't welcome him into the photograph and paid more attention to his girlfriend at the time.
"She didn't acknowledge me when it was time to pose for the photograph," Mueller said.