More than three months after OpenAI’s board of directors briefly ousted Sam Altman

, the chief executive of the high-profile artificial intelligence company, questions remain about exactly what led the board to make such a dramatic move.

A report from an outside law firm, which is expected in the coming days, could shed more light on the board’s decision as well as the chaotic five days before Mr. Altman returned to the company.

But as anticipation for the report grows, previously unreported details are emerging about the role that Mira Murati, OpenAI’s chief technology officer, played in the ouster of Mr. Altman.

Ms. Murati wrote a private memo to Mr. Altman raising questions about his management and also shared her concerns with the board. That move helped to propel the board’s decision to force him out, according to people with knowledge of the board’s discussions who asked for anonymity because of the sensitive nature of a personnel issue.

Around the same time, Ilya Sutskever, a co-founder and chief scientist of OpenAI, expressed similar worries, citing what he characterized as Mr. Altman’s history of manipulative behavior, the people said. Both executives described a hot-and-cold relationship with Mr. Altman. Though it was not clear whether they offered specific examples, the executives said he sometimes created a toxic work environment by freezing out executives who did not support his decisions, the people said.

Ms. Murati’s interactions with the board offer insight into problems festering at the senior levels of OpenAI, though both executives publicly backed Mr. Altman’s return to the company.