Chief Ashkenazi Rabbi Yonah Metzger was questioned under caution by police on Thursday, for suspicions he was involved in bribery, fraud, money laundering, and breach of trust.
Metzger is one of several suspects in the investigation that national fraud unit made public on Thursday.
As part of the investigation, on Thursday officers went to the house and office of the rabbi, and confiscated documents, computers, and other materials they believe may be linked to the allegations.
The three additional suspects in the case will be brought to the Rishon Letzion Magistrate's Court for a remand hearing at 5pm on Thursday.
In response to the investigation, Metzger's lawyers said that he presented himself for a police investigation that lasted a number of hours and that he answered all police questions.
His lawyers said that their client denied all wrongdoing.