Olympus’ CEO has resigned after the company conducted an investigation into an allegation he bought illegal drugs, finding behaviors inconsistent with company policy. This marks a stunning exit for the German native after less than two years at the helm.

The company’s shares declined more than 7% Monday, the biggest intraday slide in almost three months, after it said Stefan Kaufmann had resigned all positions effective immediately. Olympus, best known as a designer of cameras and imaging gear before a pivot into medical equipment such as endoscopes, wouldn’t comment further on the case, citing an ongoing investigation. Kyodo News reported that Japanese police were conducting their own probe.

The 56-year-old Kaufmann presided over a roughly 18% stock price climb over his tenure. But that was just about half the gains the benchmark Topix index managed over the same period. Chairman Yasuo Takeuchi will act as Olympus CEO in the interim.