Authorities arrested two sisters for allegedly hiding millions of dollars worth of cash in their garage to evade inheritance taxes, officials said Wednesday.

Prosecutors in Osaka arrested Hatsue Shimizu, 64, and Yoshiko Ishii, 55, Tuesday on suspicion of evading inheritance taxes, said Yoichi Nagai, an official of the Osaka branch of the National Tax Agency, which investigated the case with prosecutors.

Investigators found some 50 cardboard boxes containing about $56.4 million in cash in Shimizu's garage, the official said, adding some money was also found in the younger sister's home.

The two women are suspected of evading about $27.8 million in inheritance taxes, according to Nagai.

Their father, who was in the real-estate lease business, died in 2004, leaving $72.9 million to his family.

It would be the biggest inheritance tax evasion on record, according to the official.