LOS ANGELES — Only a week has passed since the Dodgers abruptly fired Ippei Mizuhara, the interpreter and constant companion of their new $700 million slugger, Shohei Ohtani.

But the biggest story of baseball’s spring is still murky — and shocking — as the regular season begins in earnest Thursday.

The scandal encompasses gambling, alleged theft, extensive deceit and the breakup of an enduring partnership between the majors’ biggest star and his right-hand man. Investigations are underway by the IRS and Major League Baseball, and Ohtani publicly laid out a version of events Monday that placed the responsibility entirely on Mizuhara.

Here are the basics as Ohtani and the Dodgers prepare for their home opener against the Cardinals on Thursday:

Why was Mizuhara fired?

Ohtani claims his close friend repeatedly took money from his accounts to fund his illegal sports gambling habit. Ohtani also says he was completely unaware of the “massive theft,” as his lawyers termed it, until Mizuhara confessed to him and the Dodgers last week in South Korea, where the team opened its regular season against the Padres.

Mizuhara has given more than one version of his path to this trouble, which was catalyzed by the IRS’ investigation of Mathew Bowyer, an alleged illegal bookmaker. Mizuhara has consistently said he has a gambling addiction, and he abused his close friendship with the Dodgers superstar to feed it.

Did Ohtani bet on sports?

That’s the biggest question to be answered in MLB’s investigation, and the two-time AL MVP emphatically says he has never gambled on sports or asked anybody to bet on sports for him.

Further, Ohtani said Monday he has never knowingly paid a bookie to cover somebody else’s bets. Mizuhara also said Ohtani does not bet, and Bowyer’s attorney said the same.

Mizuhara told ESPN on March 19 that Ohtani paid his gambling debts at the interpreter’s request, saying the bets were on international soccer, the NBA, the NFL and college football. If that were true, Ohtani could face trouble even if he didn’t make the bets himself — but ESPN said Mizuhara dramatically changed his story the following day, claiming Ohtani had no knowledge of the gambling debts and had not transferred any money to bookmakers.

MLB rules prohibit players and team employees from wagering — even legally — on baseball. They also ban betting on other sports with illegal or offshore bookmakers.

What don’t we know?

MLB’s investigation of Ohtani’s role in the events could last weeks or months, and it’s unlikely to be publicized until it’s complete.

Major questions loom

How did Mizuhara have enough access to Ohtani’s bank accounts to get the alleged millions without Ohtani knowing? Is the slugger overly trusting, or is he wildly negligent in managing his vast fortune, which includes years of lavish endorsement deals in addition to his baseball salaries? Why didn’t the team around him, including his agent, do more to prevent the possibility of the theft he claims?

Finally, where is Mizuhara? He was fired in South Korea and apparently didn’t travel home with the Dodgers. Japanese media have visited his home in Southern California to look for him.