The Tokyo District Court sentenced a former employee of Mitsubishi UFJ Financial Group (MUFG) to nine years in prison on Monday for stealing cash and valuables from customers’ safe-deposit boxes.

Yukari Yamazaki, who formerly served as a deputy branch manager at MUFG Bank, had been indicted for stealing about ¥390 million ($2.6 million) worth of property including cash and gold bars from the safe-deposit boxes of six customers at two Tokyo branches.

Local media reported that she allegedly stole even more, with the total including thefts not covered by the indictment coming to as much as ¥1.8 billion worth of assets from more than 100 customers’ boxes.

The thefts by a senior employee at Japan’s biggest bank shook confidence in the industry, especially after Mizuho Financial Group found that a former worker committed similar offenses. The incidents have increased scrutiny of the decades-old practice of depositors keeping valuables in the boxes, with financial regulators encouraging banks to prohibit the storage of cash in the containers.

MUFG has said that Yamazaki abused her managerial position to unlawfully use the bank’s spare keys to open safe boxes without customer authorization. Her long tenure in the branch sales division led to excessive reliance on her for safe-deposit box operations, the bank said. The stolen funds were used for foreign exchange margin trading, according to MUFG.