A prominent lawyer and plea deal expert said Monday that Nissan's ex-Chairman Carlos Ghosn, suspected of violating financial law, may have fallen victim to Japan's recently established plea bargaining system, leading to an arrest despite a lack of clear incriminating evidence.

Ghosn, who was dismissed Thursday as chairman of Nissan Motor Co. and removed from the same position at Mitsubishi Motors Corp. Monday, was arrested on Nov. 19 on suspicion of underreporting his income by around ¥5 billion for five years through fiscal 2014. He received nearly ¥10 billion over that period. He is also suspected of misusing company funds to pay for a luxurious lifestyle.

But Nobuo Gohara, a former prosecutor and now lawyer at Gohara Compliance and Law Office in Tokyo, believes the legal grounds for Ghosn's arrest are murky.