Diehl, 29, was arrested last month on a federal complaint charging him with wire fraud. The indictment charges him with nine counts of wire fraud and two counts of money laundering, the U.S. attorney's office said.
Diehl, who is free on a $75,000 bond, was scheduled to be arraigned Monday.
Prosecutors said Diehl offered to secure a $24 million line of credit for a construction project in Mexico if the developer deposited $2.5 million into a bank account. Diehl promised to use the money as collateral to secure a line of credit, but instead he withdrew the money to pay other people who made investments with him, the complaint said.
Diehl, who works as an offensive line coach at Mater Dei High School, used the money to pay off other investors and to run his mortgage lending and private investment companies.
An after-hours call to one of those companies, ARA Capital in Irvine, was not immediately returned.
Diehl briefly played offensive line for the Titans after attending California.
