NEW YORK (AP) — Major League Baseball has opened a formal investigation into illegal gambling and theft allegations involving Los Angeles Dodgers star Shohei Ohtani and his 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 and claims from Ohtani’s attorneys that the two-way Japanese star had been the victim of a “massive theft.”

“Major League Baseball has been gathering information since we learned about the allegations involving Shohei Ohtani and Ippei (Mizuhara) from the news media,” the commissioner’s office said in a statement Friday. “Earlier today, our Department of Investigations began their formal process investigating the matter.”

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.

The Associated Press has been unable reach Mizuhara for comment. It is not clear if he has an attorney. Mizuhara was with the team in South Korea up until his firing. It’s unknown if he left the country.

MLB established its Department of Investigations in 2008 following allegations in the 2007 report by former Senate Majority Leader George Mitchell into the use of performance-enhancing drugs in the sport. The unit investigated three-time MVP Alex Rodriguez, who was suspended for the 2014 season for violations of the drug agreement and labor contract in connection with the Biogenesis investigation.

More recently, the unit probed Dodgers pitcher Trevor Bauer, leading to a 194-game suspension in 2022 under the sport’s domestic violence, sexual assault and child abuse policy. A San Diego woman said Bauer beat and sexually abused her, an accusation the pitcher denied.

Ohtani is baseball’s bigger star, an unprecedented two-way player who has excelled at the plate and on the mound. He was a two-time AL MVP with the Los Angeles Angels before leaving as a free agent to sign a record $700 million, 10-year contract with the Dodgers in December.

Ohtani has not issued any statements and did not speak to reporters in the Dodgers clubhouse after Thursday night’s game.

The Dodgers are set to resume the regular season with their home opener next Thursday. The team has exhibition games scheduled against the crosstown Angels for Sunday, Monday and Tuesday.

Mizuhara, Ohtani’s personal interpreter and close friend, told ESPN on Tuesday that his bets were on international soccer, the NBA, the NFL and college football. MLB rules prohibit players and team employees from wagering — even legally on baseball — and also ban betting on other sports with illegal or offshore bookmakers.

“I never bet on baseball,” Mizuhara told ESPN. “That’s 100%. I knew that rule … We have a meeting about that in spring training.”

Diane Bass, Bowyer’s attorney, told the AP on Thursday that Mizuhara was placing bets with Bowyer on international soccer, but not baseball. Bass also said Bowyer had no contact with Ohtani.

The MLB gambling policy is posted in every locker room. Betting on baseball — legally or not — is punishable with a one-year ban from the sport. The penalty for betting on other sports illegally is at the commissioner’s discretion. Sports gambling is illegal in California, even as 38 states and the District of Columbia allow some form of it.

ESPN said Mizuhara told the outlet Tuesday that Ohtani had paid his gambling debts — which totaled well over $1 million — at Mizuhara’s request. After the statement from Ohtani’s attorneys saying the player was a victim of theft, ESPN says Mizuhara changed his story Wednesday and claimed Ohtani had no knowledge of the gambling debts and had not transferred any money to bookmakers.

“I’m terrible (at gambling). Never going to do it again. Never won any money,” Mizuhara said. “I mean, I dug myself a hole and it kept on getting bigger, and it meant I had to bet bigger to get out of it and just kept on losing. It’s like a snowball effect.”

It’s the biggest gambling scandal for baseball since Pete Rose agreed to a lifetime ban in 1989 after an investigation for MLB by lawyer John Dowd found Rose placed numerous bets on the Cincinnati Reds to win from 1985-87 while playing for and managing the team.