Scandal-wracked Olympus and three of its former top executives pleaded guilty in court Tuesday over charges that they covered up losses worth $1.7 billion stemming from bad investments. Former president Tsuyoshi Kikukawa apologised in Tokyo District Court and said he would take "full responsibility" for the crime that came to light when his British successor blew the whistle. "All responsibility rests with me as the president. I shall take full responsibility," Kikukawa told the court at its first hearing. "I sincerely apologise for all the troubles that I caused," he said. The case was originally thrust into the spotlight last year by Michael Woodford, who replaced Kikukawa at the head of the company and became the first foreigner to lead the camera and endoscope maker. He initially internally questioned $1.7 billion in losses at the firm, but said he was abruptly demoted shortly before exposing a scheme that saw huge losses moved off the firm's balance sheet. Kikukawa's guilty plea was joined by two fellow former Olympus officers, ex-vice president Hisashi Mori and former auditor Hideo Yamada, and the company itself. Prosecutors have alleged that Olympus started using a complex accounting mechanism to hide losses that came from bad investments made in the 1990s, with the firm's top officers including former presidents, approving the moves. According to the indictment, Kikukawa, Mori and Yamada conspired with outside advisers to hide the losses via purchases of foreign companies and overpriced consulting fees.