So Mardukas just walks around the house w/a money-belt (spoiler)
When De Niro picks him up at his house in NY he presumably told him to just throw on a coat so they could leave, but at the end when he frees him Mardukas pulls a money belt he's been wearing the whole time. So the Duke was just lounging with his wife at their home wearing a money-belt? Seems far-fetched.