TOKYO — Nissan on Wednesday cleared the senior executive in charge of its legal department of “inappropriate involvement” in the investigations surrounding Carlos Ghosn, the company’s former chairman, after a series of reports about possible conflicts of interest.

In a statement, Nissan said Hari Nada — who is expected to be a key witness against Mr. Ghosn in his trial over financial wrongdoing — would remain a senior vice president and continue to report to its acting chief executive, Yasuhiro Yamauchi.

Mr. Nada’s supervision of the company’s legal department and security office, as well as other roles, was transferred to Hitoshi Kawaguchi, an executive vice president, the statement said. Mr. Nada was given an added title as senior adviser overseeing special projects.

Nissan said it had “found no evidence of inappropriate involvement by Nada in the internal investigation into executive misconduct led by former chairman Carlos Ghosn and others.” The statement added that “the change is aimed to avoid undue suspicion and to enable him to focus on important tasks for the company, such as forthcoming legal action.”