Almost three weeks after his shock arrest, former Nissan Chairman Carlos Ghosn's relationship with his former protege is emerging as key to determining what may have triggered the investigation that has put the car industry titan in a Tokyo jail cell.

Ghosn, who was ejected from the top post shortly after his arrest, planned for months to shake up senior management at the automaker and had made known his plans to replace Chief Executive Officer Hiroto Saikawa, The Wall Street Journal reported Sunday, citing unidentified people familiar with the situation. Ghosn, who promoted the Nissan lifer to the CEO position in 2017, wanted to carry out his plan at a board meeting in November, one of the people told the paper.

But people familiar with Ghosn's case and with Nissan's operations said there was no plan to eject Saikawa last month, or before the end of his term, which was due to run until April next year.