TOKYO — Concern is mounting within Nissan Motor Co. that the upcoming trial of its fired chairman, Carlos Ghosn, will turn an embarrassing spotlight on the man who now runs the company — CEO Hiroto Saikawa.

Some people familiar with the case now worry that Saikawa's purported awareness of some of Ghosn's financial arrangements at Nissan, which are the core of the Japanese government's charges against him, could jeopardize the legal case.

The unease centers on claims that, before he became CEO, Saikawa may have signed several documents that are pivotal in accusations against Ghosn, people familiar with the matter told Automotive News. The former chairman was arrested and jailed in November and faces three indictments accusing him of financial wrongdoing during his years at Nissan. Ghosn denies any wrongdoing and is now free on bond in Tokyo.

The documents concern millions of dollars in deferred executive compensation promised to Ghosn and other benefits he received, such as housing paid for with company money, the people said.

Saikawa's signature on related documents was reported by Japan's Asahi newspaper in December. But their existence has assumed new urgency because prosecutors must now turn the documents over to Ghosn's defense team as part of pretrial discovery. Ghosn's lawyers were expected to have the documents in hand as early as Friday, March 15, two people said.

"There is a concern in the company that when those documents come to light, whether through a trial or now, it will embarrass the company and it will embarrass Saikawa because, obviously, he signed those things," one person said.