The interpreter for Shohei Ohtani, the biggest star in baseball and one of the most famous people in Japan, has been fired after lawyers for the player said there had been a “massive theft” from the slugger’s account.

ESPN reported that several sources said Ippei Mizuhara had run up large debts to a Californian bookmaker. Initially a spokesperson for the player said Ohtani had transferred $4.5m to cover Mizuhara’s debts. But when ESPN asked further questions, the spokesperson backed away from their claim and said Ohtani’s lawyers would soon make a statement.

“In the course of responding to recent media inquiries, we discovered that Shohei has been the victim of a massive theft, and we are turning the matter over to the authorities,” read the statement from Berk Brettler LLP on Wednesday.

Mizuhara told ESPN on Wednesday he had been instructed not to comment on the matter but did not say where those instructions had come from.

Sports betting is legal in 40 US states but is still outlawed in California, where Ohtani plays for the Los Angeles Dodgers. MLB players and staff are allowed to bet on sports other than baseball but are forbidden from gambling with illegal bookmakers. Any violation of the rules would leave players or staff subject to punishment from the MLB commissioner, Rob Manfred. There is no suggestion that Ohtani has ever gambled himself.

Bowyer’s attorney, Diane Bass, told ESPN: “Mr Bowyer never met or spoke with Shohei Ohtani.”

Mizuhara had initially said on Tuesday that Ohtani had helped him cover the gambling debts and ESPN saw two documents containing payments of $500,000 in Ohtani’s name from September and October. ESPN reports the payments were made to an associate of Mathew Bowyer, whose bookmaking operation is under investigation by federal investigators.

“Obviously, he [Ohtani] wasn’t happy about [the debt] and said he would help me out to make sure I never do this again,” Mizuhara said on Tuesday, before Wednesday’s developments. “He decided to pay it off for me. I want everyone to know Shohei had zero involvement in betting. I want people to know I did not know this was illegal. I learned my lesson the hard way. I will never do sports betting ever again.”

Mizuhara added that he had never bet on baseball.

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

Ohtani and Mizuhara are close friends beyond their working relationship. Mizuhara has been Ohtani’s translator since the star moved from Japan to play for the Los Angeles Angels in 2018. Ohtani joined the Dodgers in December on a 10-year, $700m deal. He made his Dodgers debut on Wednesday in a victory over the San Diego Padres in South Korea, and is hugely popular in Japan.

ESPN said MLB is investigating the case. The Dodgers have yet to comment.