Donnie Nelson has filed a lawsuit against the Dallas Mavericks, alleging Mark Cuban fired him as retaliation for reporting that Cuban's chief of staff sexually harassed and sexually assaulted his nephew during a job interview in 2020.

The lawsuit also alleges that Cuban offered Nelson, who was fired in June, $52 million to withdraw a wrongful termination claim and sign a confidentiality statement related to the alleged harassment and abuse of his nephew.

Nelson says Jason Lutin, described in the lawsuit as Cuban's "right-hand man" and who still works for the team, assaulted and harassed his nephew in a hotel room during the 2020 All-Star Weekend in Chicago. The nephew, a man in his 20s who is not identified in the lawsuit, had been invited by Lutin to his hotel room, the lawsuit says.

Cuban denied Nelson's allegations in an email to ESPN.

"Everything in that filing is a lie," Cuban wrote. "We did multiple complete investigations and the only person that did not live up to the standards of the Dallas Mavericks was Mr. Nelson. He was fired as a result. He was well aware of the investigation. He refused to fully participate. I will say it again, everything he said is a lie."

On June 13, Cuban notified Nelson that he was firing him. Media reports at the time said Nelson was fired amid "internal friction" with Haralabos Voulgaris, the former professional gambler hired in 2018 to be the Mavericks' director of quantitative research and development.

The lawsuit alleges a direct link between "Nelson's complaint and report of Lutin's improper activities" and Cuban's withdrawal of a 10-year, $66 million contract offer to Nelson in September 2020.

Nelson worked for the Mavericks for 24 seasons.