The former MUFG Bank employee suspected of stealing customer assets regularly paid interest to pawnshops for the gold ingots she had stolen and pledged, it was learned Wednesday.

The 46-year-old suspect, Yukari Imamura, allegedly stole the assets of at least 60 customers worth ¥1.7 billion ($11 million) from the safe-deposit boxes they used at the bank. Of the total, gold ingots are believed to account for about ¥700 million.

Tokyo's Metropolitan Police Department suspects she paid interest to prevent the pawned gold ingots from being lost so that she could collect and return them to safe-deposit boxes when necessary.

The pawnbroker business law stipulates that the ownership of pawned goods be transferred to the pawnshop if interest and other necessary payments are not made within at least three months from the time of pawning.

According to investigative sources, Imamura deposited in several pawnshops gold ingots worth several hundred million yen that she had stolen.

The bank recovered all of the pawned gold ingots after learning of her massive thefts.

According to the police, Imamura used the cash she obtained through the thefts for foreign exchange margin trading and horse racing. She incurred losses of at least ¥1 billion from the currency trading.

Imamura told investigators that she thought that gold ingots would allow her to obtain a lot of cash. The police believe she chose to steal gold ingots, which can be quickly converted into cash, so that she could refill the safe-deposit boxes from which she stole cash on the day a customer was scheduled to check their box, thereby evading detection.

Imamura was arrested on Jan. 14 for allegedly stealing about 20 kilograms of gold ingots, worth about ¥260 million, from two customers' safe-deposit boxes at the Nerima branch in late September last year.