Major League Baseball has opened a formal investigation into illegal gambling and theft allegations involving Los Angeles Dodgers star Shohei Ohtani's interpreter, Ippei Mizuhara.

Mizuhara was let go from the team Wednesday following reports from the Los Angeles Times and ESPN about his alleged ties to an illegal bookmaker.

Ohtani and the Dodgers were in Seoul, South Korea, for their opening series against the San Diego Padres when reports were published about alleged ties between the 39-year-old Mizuhara and an illegal bookmaker. The teams returned to the U.S. after Thursday night's game and MLB did not make a public comment until announcing the investigation on Friday.

The IRS confirmed Thursday that Mizuhara and Mathew Bowyer, the alleged illegal bookmaker, are under criminal investigation through the agency's Los Angeles Field Office. IRS Criminal Investigation spokesperson Scott Villiard said he could not provide additional details.

WATCH | Ippei Mizuhara, interpreter to baseball superstar Shohei Ohtani, is fired: 

Shohei Ohtani's interpreter fired after alleged illegal gambling, theft from superstar

Shohei Ohtani's long-time friend and interpreter Ippei Mizuhara has been fired by the Los Angeles Dodgers after allegations of illegal gambling totalling several million dollars. Initial reports said the MLB superstar paid off that debt, but there are now accusations the money was stolen.