The pop star and her longtime producer are still embroiled in their contentious lawsuit: She is suing him, alleging he drugged and raped her and abused her for years; he vehemently denies the allegations, countersuing for breach of contract and defamation.
On Thursday, Billboard published an interview with Kesha's mother, Pebe, who alleges Luke "basically owns" Kesha and that "she was a prisoner" to her longtime collaborator.
"I do remember her calling me from the plane telling me that she was so drunk, and [how] Dr. Luke came over and started making out with her and was all over her," Sebert says. "She told me she felt terrible and was trying to get away from him and then vomited.
"I wanted Kesha to come forward a long time ago and end this relationship with Dr. Luke immediately after the [alleged] rape. But if she wanted to have a shot at the music business, she had no choice but [to work with him]."
Luke's attorney, Christine Lepera, did not respond to the allegations; however, she did on Thursday reissue a statement to PEOPLE originally sent to Billboard about Luke's past rapport with Kesha (born Kesha Rose Sebert, 29) and her mom.
"Luke did numerous favors to advance the careers of Kesha's siblings as well as Pebe herself," Lepera said. "Indeed, Pebe acknowledged Luke's generosity and expressed her warmth toward him in private correspondence when she wrote 'You are part of our family, and I hope you know, as much as you have been there for Kesha and me, that we will always be there for you, as family, and friends, if you need anything,' 'You have changed our lives forever' and 'I know you are going to be a great dad.'
"No mother would make such statements about someone who had raped her daughter," Lepera added.
Luke (born Lukasz Gottwald, 42) signed Kesha to his label, Kemosabe Records, when she was 18 and produced her 2010 breakout album Animal, which included the radio hits "TiK ToK" and "Your Love Is My Drug." He also produced her followups – the Cannibal EP and Warrior – and according to his lawyer's statement, they renegotiated her contracts after his alleged assault against her.
"Kesha's gratitude toward Luke was expressed in private correspondence when she wrote, 'Thank you 4 helping me make my WILDEST dreams come true,'" Lepera added in the statement.
Kesha first filed her lawsuit in October 2014, after emerging from rehab for an eating disorder. Around that time, Pebe told PEOPLE she believed Luke was behind her daughter's emotional distress.
"Dr. Luke told a friend of ours he thought she looked like a refrigerator on her latest video, and could she please try to control her weight," she told PEOPLE at the time. "After she went on a 14-day juice cleanse, he said, 'Thank God you finally got rid of the weight! We've all been talking about it!' So she felt like she couldn't trust anyone."
In the complaint, Kesha claimed Dr. Luke "made repeated sexual advances toward her. She claims he would force her to use drugs and alcohol to remove her defenses."
Last month, Luke took to Twitter to once again deny the accusations, writing: "I didn't rape Kesha and I have never had sex with her. Kesha and I were friends for many years and she was like my little sister. Kesha has denied under oath the horrible allegations now being made against me."
As the lawsuit rages on, many of her musical peers – from Kelly Clarkson and Adele to Taylor Swift and Demi Lovato – have spoken out in support of Kesha.
On Monday, Lady Gaga said Kesha is being "very publicly shamed" for her battle against Luke, adding: "In any other business, if you were to report that anything happened to you to the human resources department, it would be dealt with. But we don't have a human resources department, we don't have a union as artists, we're just fighting for ourselves."
Pebe and reps for Kesha did not immediately respond to PEOPLE's request for comment.