September 2, 2025 – SANTA ANA, CA – An Orange County man was sentenced on Friday to 12 months and one day in federal prison for running an illegal gambling business that took in unlawful sports bets, including from then-current and former professional athletes as well as a now-imprisoned former Major League Baseball (MLB) Japanese-language interpreter.

Mathew R. Bowyer, 50, of San Juan Capistrano, was sentenced by United States District Judge John W. Holcomb, who also ordered him to pay $1,613,280 in restitution.

Bowyer pleaded guilty in August 2024 to one count of operating an unlawful gambling business, one count of money laundering, and one count of subscribing to a false tax return.

Bowyer operated an unlicensed and illegal bookmaking business that focused on sports betting and violated a California law that prohibits bookmaking. Bowyer’s gambling business remained in operation for at least five years until October 2023 and at times had more than 700 bettors.

“[Bowyer’s] crimes were not a single indiscretion, but instead a multi-year operation that raked in millions of dollars for [Bowyer] and his associates to gamble and live an extravagant lifestyle, often through the exploitation of people [Bowyer] recognized were addicted and extending themselves beyond their means, money that was routed through multiple accounts and ultimately not reported to the government on [Bowyer’s] taxes,” prosecutors argued in a sentencing memorandum. 

Bowyer operated this business out of various locations in Los Angeles and Orange counties as well as in Las Vegas. Bowyer also employed agents and sub-agents – including casino hosts – who worked for his illegal gambling business who were paid a portion of the losses that bettors incurred and paid. His unlawful business used several Costa Rica-based websites and a call center so agents and customers could place and track bets. At times, Bowyer operated his illegal business while gambling at a casino – identified in court documents as “Casino A” – and sometimes paid his agents commission in Casino A chips.

One of Bowyer’s clients was Ippei Mizuhara, who is serving a 57-month federal prison sentence after pleading guilty in June 2024 to one count of bank fraud and one count of subscribing to a false tax return. Mizuhara was the Japanese-language interpreter and de facto manager of MLB superstar Shohei Ohtani. Mizuhara admitted to stealing nearly $17 million from Ohtani to pay off gambling debts and failing to pay tax on his gambling income. 

From September 2021 to January 2024, Mizuhara placed at least 19,000 bets with Bowyer’s illegal gambling business through one of the betting websites Bowyer used for it. During this period, Mizuhara had total winning bets of at least $142,256,769, and total losing bets of at least $182,935,206, leaving Mizuhara owing approximately $40,678,436. On a regular basis during this period, Bowyer would increase Mizuhara’s betting limits.

From February 2022 to January 2024, Bowyer directed Mizuhara to make payments of at least $16.25 million to Bowyer-controlled bank accounts, all of which were proceeds of Bowyer’s illegal gambling business. Of these illegal proceeds, Bowyer transferred or directed the transfer of least $9.3 million to a casino in the form of wire transfers as payment for markers for Bowyer and his associates.

Other Bowyer gambling business customers included “Individual B,” a professional baseball player for a Southern California-based baseball club, and “Individual C,” a former minor-league baseball player.

Bowyer knowingly and willfully falsely reported his taxable income to the IRS on his tax return for the year 2022. On that year’s tax return, Bowyer reported $607,897 in total income. His unreported income for that year was $4,030,938, which was income from his illegal gambling business, including $3.8 million in wire transfers into one of his bank accounts, which he did not declare on his tax return. As a result of the false information Bowyer provided, he owes additional taxes of $1,613,280 for the tax year 2022, not including interest and penalties.

As part of his plea agreement, Bowyer agreed to forfeit $257,923 in U.S. currency and $14,830 in casino chips seized by law enforcement in October 2023.

IRS Criminal Investigation and Homeland Security Investigations investigated this matter.

Assistant United States Attorneys Kristen A. Williams of the Major Frauds Section and Jonathan S. Galatzan of the Asset Forfeiture and Recovery Section prosecuted this case.

Source: DOJ Release