Dozens of investigators have raided buildings belonging to the Japanese company Olympus in Tokyo.
Their inquiry revolves around an accounting scandal that hid 1.3 billion euros of losses from shareholders and customers over the last two decades.
Investigators also headed to the luxury development where a former company president lives.
The inquiry is a joint effort by Tokyo’s police, prosecutors and financial regulators.
Their efforts gathered pace after a panel appointed by Olympus said that two senior former executives masterminded the plan with investment bankers.
The panel also concluded that three former company presidents knew about the cover up. One of them resigned over the scandal in October.
Last week Olympus filed five year’s worth of revised accounts to the Tokyo stock exchange revealing a much depleted balance sheet.
It could yet be delisted from the exchange.