Sources say Tokyo prosecutors have obtained email correspondence showing how part of the funds Nissan paid to a dealership in Oman were allegedly channeled to former chairman Carlos Ghosn.
Prosecutors arrested Ghosn for the fourth time on Thursday on suspicion of aggravated breach of trust.
They allege that Ghosn caused Nissan losses worth more than 5 million dollars through the payments to the Omani dealership.
Prosecutor suspect Ghosn siphoned off part of the payments through an account belonging to a dummy company in Lebanon.
Sources say prosecutors have obtained email records of the money trail.
They say the records show that about 27 million dollars were transferred from the account to a US-based investment-related firm run by Ghosn's son, and about 8 million dollars to a company represented by Ghosn's wife.
Prosecutors are said to have obtained the email records from Nissan, which is cooperating with the investigation.
Ghosn is reportedly denying the allegations.