Major League Baseball has announced a formal investigation into L.A. Dodger star Shohei Ohtani‘s role in a gambling scandal involving his former interpreter, Ippei Mizuhara.

Earlier this week, Mizuhara was fired by the Dodgers after it came to light that at least $4.5 million in wire transfers was sent from Ohtani’s bank account to an alleged bookmaking operation that is under federal investigation.

Things became complicated after Ohtani’s handlers allowed Mizuhara to grant an interview to ESPN. In that interview, Mizuhara said Ohtani had paid off his interpreter’s gambling debts with the transfers. However, the handlers then disavowed that interview, and Ohtani’s attorneys said the slugger had been the victim of a “massive theft” of the funds.

How that happened remains a mystery.

So far, it appears law enforcement is not involved in any investigation. ESPN reports Ohtani’s representatives said Thursday that they had officially submitted the allegation to law enforcement, but did not say to which authorities. Sources told ESPN that neither the California Bureau of Investigation nor the FBI was working the case.

Digging further, ESPN reported neither the Los Angeles Police Department and district attorney’s offices in Los Angeles and Orange counties were not investigating, and they indicated it was most likely a federal matter. The U.S. Attorney’s Office for the Central District of California declined to comment.

Ohtani can refuse cooperation as a member of the MLB Players Association.

MLB said in a statement that its department of investigations began formally investigating the matter Friday.

Neither Ohtani or Mizuhara have been charged with a crime. Ohtani is expected to remain on the Dodgers’ active roster while the league’s investigation unfolds.