U.S. authorities intend to file criminal charges against a financier in connection with an international scandal rooted in Malaysia that they believe could be one of the largest financial frauds ever, according to people familiar with the matter.

The scandal involves a state fund called 1Malaysia Development Bhd., or 1MDB, and the focus of the criminal investigation is Jho Low, a flamboyant financier the U.S. Justice Department portrayed in civil asset-seizure lawsuits in July as central to an alleged plot to siphon billions...