An independent investigation commissioned by OpenAI’s nonprofit board has found that CEO Sam Altman’s conduct “did not mandate removal.” After surviving an attempted boardroom coup in November, he will now rejoin the board.

In a press release, board chair Bret Taylor said the law firm WilmerHale interviewed board members, employees, and reviewed “more than 30,000 documents” to reach the conclusion that Altman and co-founder Greg Brockman “are the right leaders for OpenAI.”

In addition to Altman, Taylor also announced three more OpenAI board members: Sue Desmond-Hellmann, the former CEO of the Bill and Melinda Gates Foundation; Nicole Seligman, a former legal executive at Sony; and Fidji Simo, the CEO of Instacart. They will join Taylor, Altman, Quora CEO Adam D’Angelo, and Larry Summers in governing OpenAI’s nonprofit parent company.

For those seeking to better understand why Altman was suddenly fired from his perch last fall, OpenAI’s public summary of the WilmerHale investigation is frustratingly light on details. The law firm said the board believed it “would mitigate internal management challenges” by firing Altman suddenly, and that the “decision did not arise out of concerns regarding product safety or security, the pace of development, OpenAI’s finances, or its statements to investors, customers, or business partners.”

The summary of the investigation uses the same vague language that OpenAI’s previous board published to justify its decision to fire Altman: that the incident, which I’m told OpenAI employees refer to as “The Blip,” was a “consequence of a breakdown in the relationship and loss of trust between the prior Board and Mr. Altman.” WilmerHale also found that the prior board moved “without advance notice to key stakeholders, and without a full inquiry or an opportunity for Mr. Altman to address the prior Board’s concerns.”

On a short video call with reporters Friday, Altman apologized for believing that “a former OpenAI board member was harming OpenAI through their actions” but declined to go into more detail. It has been widely reported that he tussled with ex-board member Helen Toner over an academic paper she co-authored that was critical of OpenAI’s approach to safety, and that others expressed concerns about the conflicts of interest posed by Altman’s other investments.

OpenAI said on Friday that it planned to “strengthen” its conflict of interest policy for employees without elaborating, and that it would also create a whistleblower hotline for employees and contractors.

During the call with reporters, Altman appeared cheerful while sitting next to Bret Taylor. At one point, he was asked about the employment status of co-founder and chief scientist Ilya Sutskever, who played a key role in the failed coup but changed sides when the majority of OpenAI employees threatened to quit if Altman didn’t return.

Sutskever has since gone quiet, leading to questions about his involvement with the company going forward. On the call, Altman said there was “nothing to announce” but that “Ilya is awesome,” and “I hope we work together for the rest of our careers.”

He said that recent “leaks” intended “to pit us against each other” had “not worked,” and that he is “pleased this whole thing is over.”