In their complaint filed Thursday, federal investigators said they had conducted forensic reviews of the phone of Shohei Ohtani's former interpreter, Ippei Mizuhara, as well as devices belonging to "Bookmaker 1," assumed to be Southern California bookie Mathew Bowyer, and "Bookmaker 2," an associate of Bowyer's.

Prosecutors accused Mizuhara of bank fraud and said he stole more than $16 million over several years from Ohtani. Before he was fired by the Los Angeles Dodgers on March 20, Mizuhara had interpreted for Ohtani since the superstar moved to the United States in 2018.

Texts among the parties, as laid out in the 37-page complaint, depict Mizuhara's apparent descent into an uncontrolled sports betting addiction, and the bookie who kept extending his credit as long as Mizuhara covered his losses.

Getting started

Mizuhara has said he met Bowyer at a poker game in San Diego in 2021. According to the complaint, on or about Sept. 8, 2021, "Bookmaker 2" provides Mizuhara an account number, password and URL for an illegal betting website. About two weeks later, Mizuhara messages Bookmaker 2: "Ive just been messing around with soccer, theres games on 24/7 lol. I took UCLA but they lost outright!!!"

The same day, Mizuhara messages Bookmaker 2: "How does the withdrawing and paying work?" Bookmaker 2 responds later that day, "He pays and collects as the week ends Sunday night[.] Whatever you are up or down Sunday night you pay or receive[.] Last week you were down and he rolled it as hes ok with it[.] I say have a settle figure[.] Meaning pick a number you want to settle at either way[.]"

On Oct. 27, 2021, Bookmaker 2 messages Mizuhara: "[Bowyer] asked me to reach out to you . . . he sees you playing and wants to settle this by tomorrow[.] I can meet you or one his runners can." Mizuhara responds, "I'm back in Anaheim now, is there any way to pay [Bowyer] via credit or debit card . . . I can wire the amount to his bank account. Do you know what bank he uses?"

Through the fall, text traffic indicates Mizuhara struggling to transfer funds to cover his debt because of bank limits or other issues. On or about Nov. 9, he tells Bookmaker 2: "tried almost every option possible and none of it is working. ... this is super stressing."

The next day, he tells Bookmaker 2 that he is "able to send 40k," adding that it looks as if the method works "but I can only send 40k at a time."

Losses mount

The federal complaint indicates Mizuhara's losses mounted almost immediately. He repeatedly asks the bookies to "bump" his account, or increase his line of credit.

On Jan. 2, 2022, Mizuhara asks Bookmaker 2 if [Bowyer] could "reload my account? I lost it all." Bookmaker 2 responds, "[Bowyer] bumped you 50k." Thirteen days later, Mizuhara texts Bookmaker 2 again: "F--- I lost it all lol . . . can you ask [Bowyer] if he can bump me 50k? That will be my last one for a while if I lose it."

By Feb. 4, 2022, Mizuhara texts: "I made another transfer for 300k today since I lost the other 100k already." Later that day, he confirms, "Wire went through!"

Over the next two years, according to the complaint, Mizuhara averaged 25 bets per day, ranging from $10 to $160,000 per bet, between December 2021 and this January -- some 19,000 bets in all. His texts during this time show increasing desperation to catch up.

Some highlights of that time:

March 10, 2022: Mizuhara messages Bowyer asking him to reduce his credit from $300,000 to $100,000. "I'll get too reckless with 300," he says.

May 2022: Text messages from Mizuhara indicate he's on a "bad run." Despite Mizuhara owing Bowyer over $1 million, Bowyer continually increased Mizuhara's betting limits, investigators said.

Nov. 14, 2022: Mizuhara texts Bowyer: "I'm terrible at this sport betting thing huh? Lol . . . Any chance u can bump me again?? As you know, you don't have to worry about me not paying!!"

Dec. 9, 2022: Mizuhara texts Bowyer: "Can u bump me last 200? I swear on my mom this will be the last ask before I pay it off once I get back to the states. Sorry for keep on asking. . . ." Bowyer responds: "Np done bud. Merry Christmas."

May 20, 2023: Bowyer texts Mizuhara: "I know you've been on a bad run. I don't mind bumping u, I just want to verify that you can send at least 2M on June 1."

June 22, 2023: Mizuhara texts Bowyer: "I got my ass kicked again lol . . . . Any chance I can get one last bump? This will be my last one for a while if I lose it. . . ." Bowyer responds: "Ok bud. I just want to be able to communicate with my partner so he knows expectations. If I can assure him that minimum 500 will be sent every week I can do the bump to whatever you want? It's just imperative that the 500 is sent every week as you can imagine the figures are very high and just don't want to not be able to deliver what I tell him[.] FYI I have already paid out of my pocket to him half of the balance that is on the account so whatever is lost every week I have to give him half of the balance that's why I'm asking these direct important questions."

June 24, 2023: Mizuhara texts Bowyer: "I have a problem lol. . . . Can I get one 13 last last last bump? This one is for real. ... Last one for real[.]" Bowyer responds, "Done. I have the same problem. To be honest with you Ippie, as long as you can guarantee the 500 every Monday I'll give you as much as you want because I know you're good for it[.] again I just have to clean it up with my partner and that's one reason why I was asking before."

In the complaint, an investigator testified that wagers for Mizuhara's account, "35966" as reflected on a bookie's spreadsheet, reflect total winning bets of about $142 million, total losing bets of about $183 million, leaving a total negative balance of about $40.7 million.

Paybacks and veiled threats

According to the complaint, Mizuhara was attempting to pay back his debt from Ohtani's account in a series of weekly $500,000 transactions, but after making some payments he stops and the tenor of texts with Bowyer shifts.

On June 20, 2023, he texts Bowyer: "It looks like I can only send 500 per week. ... I put in a wire for 500 earlier today so it should be in your account by tomorrow. . . . does 500/week work for you?"

Federal authorities raid Bowyer's house in October and seize cash, computers and phones, according to a search warrant obtained by ESPN. On or about Nov. 17, 2023, Bowyer texts Mizuhara: "Hey Ippie, it's 2 o'clock on Friday. I don't know why you're not returning my calls. I'm here in Newport Beach and I see [Ohtani] walking his dog. I'm just gonna go up and talk to him and ask how I can get in touch with you since you're not responding? Please call me back immediately."

Two days later, Mizuhara texts Bowyer: "I'm gonna be honest, I ended up losing a lot of money on crypto the last couple years and I took a huge hit obviously with the sports too. . . . Just wanted to ask, is there any way we can settle on an amount? I've lost way too much on the site already . . . of course I know it's my fault."

On Dec. 15, Bowyer texts Mizuhara, stating "I know ur busy but u Need to show some respect. I put my neck out here. Call me by Tonight. I don't care what time or how late it is." Mizuhara responds the same day: "I'm so sorry bro . . . I really don't mean to disrespect you at all I promise . . . it's just been super super busy . . . and I've got other issues on the side going on too. everything has just been really really tough recently."

This past Jan. 6, the complaint states, Bowyer texts Mizuhara: "you're putting me in a position where this is going to get out of control. If I don't hear from you by the end of the day today it's gonna [sic] be out of my hands." Mizuhara responds: "My bad man. . . . I just got back from Japan two days ago and I'm leaving tomorrow again . . . I'll be back in mid January. To be honest with you, I'm really struggling right now and I need some time before I start to make payments."

From January to March, Mizuhara spends about $325,000 of Ohtani's money on approximately 1,000 baseball cards, and has them mailed to the Dodgers clubhouse under the alias "Jay Min," the filing says. Mizuhara buys the memorabilia, which included cards for Yogi Berra, Juan Soto and Ohtani, with the intent to resell it, according to the affidavit.

On March 20, news breaks that at least $4.5 million was transmitted from Ohtani's account to Bowyer's operation. Mizuhara first tells ESPN that Ohtani paid his debts before changing his story hours later to say Ohtani had no knowledge of his gambling. Mizuhara asks Bowyer if he has seen the media reports. Bowyer responds, "Yes, but that's all bulls---. Obviously you didn't steal from him. I understand it's a cover job I totally get it," Mizuhara responds, "Technically I did steal from him. it's all over for me."

ESPN's Tisha Thompson contributed to this report.