Boston Celtics majority owner Wyc Grousbeck said Friday that the season-long suspension of head coach Ime Udoka came after an outside investigation turned up "substantial" evidence that Udoka had violated team rules.

The suspension was the result of what ESPN reported was a consensual relationship with an unidentified female staff member. Grousbeck and team president Brad Stevens addressed the media Friday but did not confirm the reason for the suspension.

Grousbeck said once the team heard reports of potential rules violations by Udoka, the Celtics brought in a law firm to conduct an independent investigation.

"We have strong values at the Celtics and we are doing our very best to uphold them here," he said.

"I personally feel that this is well warranted and appropriate, backed by substantial research and evidence and facts, and so I'm standing by the decision," he continued.

Grousbeck said Udoka's suspension will run through June 30. While he did not state whether the suspension was unpaid, he said it came with a "significant financial penalty."

And he also didn't guarantee that Udoka, 45, ever would return to the bench.

"We will make a determination at a later time about Ime's future with us," he said.

Stevens, who coached the Celtics from 2013-21 before moving upstairs, confirmed 34-year-old Joe Mazzulla, a Udoka assistant coach, will lead the Celtics this upcoming season

"It's not an easy timing for him or the rest of staff, but he's an exceptionally sharp and talented person," Stevens said.

While the Celtics executives didn't confirm a relationship with a woman was the cause of the suspension, Stevens spoke emotionally as he apologized to female staff members. On Thursday, speculation on social media ran rampant about which woman could have been involved with Udoka, with users posting photos of various team employees.

"We have a lot of talented women in our organization, and I thought yesterday was really hard on them," Stevens said. "I think that you know nobody can control Twitter speculation, but I do think that we as an organization have a responsibility to make sure we're there to support them now because a lot of people were dragged unfairly into that."

In his first season as head coach in 2021-22, Udoka led the Celtics to the NBA Finals, where they lost to the Golden State Warriors in six games. Boston finished the regular season with a 51-31 record before beating the Brooklyn Nets, Milwaukee Bucks and Miami Heat in the playoffs.

Udoka previously served as an assistant coach for the San Antonio Spurs (2012-19), Philadelphia 76ers (2019-20) and Nets (2020-21) following a seven-year playing career in the NBA.

He issued a statement on Thursday.

"I want to apologize to our players, fans, the entire Celtics organization, and my family for letting them down," he said. "I am sorry for putting the team in this difficult situation, and I accept the team's decision."

Udoka has been engaged to actress Nia Long since 2015, and they have a son. On Friday, she made her first statement about the matter.

"The outpouring of love and support from family, friends and the community during this difficult time means so much to me," Long told People magazine. "I ask that my privacy be respected as I process the recent events. Above all, I am a mother and will continue to focus on my children."