Tokyo prosecutors said on Wednesday they had indicted former Olympus Chief Executive Stefan Kaufmann over alleged violations of law concerning controlled substances.
A spokesperson at the Tokyo District Public Prosecutors Office did not give any further details.
Kaufmann was forced to resign last month after the allegation surfaced that he bought illegal drugs.
Reuters has not been able to reach Kaufmann for comment.
Kaufmann, a German national who took the helm in April last year, had been tasked with expanding Olympus' medical equipment business after preceding CEO Yasuo Takeuchi steered the company through years of asset sales.
Ahead of the news of Kaufmann's indictment, shares in Olympus closed down 1.9%, while the benchmark Nikkei average fell 0.8%.
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