An Orange County man was sentenced to just over one year in federal prison for operating an illegal sports-betting business and failing to report millions of dollars in income. Mathew R. Bowyer, 50, of San Juan Capistrano, received a sentence of 12 months and one day from 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 charges that included operating an unlawful gambling business, money laundering, and subscribing to a false tax return. His bookmaking operation violated California law by taking illegal sports bets for at least five years until October 2023 and had more than 700 bettors at times.
“[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.
The gambling ring operated out of locations in Los Angeles and Orange counties as well as Las Vegas. Bowyer used agents—including casino hosts—who received commissions based on bettor losses. The business relied on Costa Rica-based websites and a call center for placing bets. Sometimes agents were paid with casino chips.
Among Bowyer’s clients was Ippei Mizuhara, the former Japanese-language interpreter for MLB player Shohei Ohtani. Mizuhara is serving a 57-month federal prison sentence after pleading guilty to bank fraud and filing a false tax return related to stealing nearly $17 million from Ohtani to pay off gambling debts.
From September 2021 through January 2024, Mizuhara placed about 19,000 bets with Bowyer’s operation using one of its betting websites. In this period, Mizuhara had total winning bets exceeding $142 million and losing bets over $182 million—leaving him owing approximately $40 million. Prosecutors said Bowyer regularly raised Mizuhara’s betting limits during this time.
Between February 2022 and January 2024, Bowyer instructed Mizuhara to send at least $16.25 million into bank accounts he controlled—all proceeds from illegal gambling activity. Of those funds, at least $9.3 million was transferred or directed as payment for markers at casinos.
Other clients included “Individual B,” identified as a professional baseball player for a Southern California team, and “Individual C,” described as a former minor-league baseball player.
In addition to running the illegal betting business, Bowyer filed false tax returns by underreporting his income for tax year 2022 by more than $4 million—declaring only about $600,000 while failing to disclose millions earned from the operation.
As part of his plea agreement with authorities, Bowyer agreed to forfeit cash totaling more than $257,000 along with almost $15,000 in casino chips seized during an October 2023 law enforcement action.
The case was investigated by IRS Criminal Investigation and Homeland Security Investigations. Assistant United States Attorneys Kristen A. Williams (Major Frauds Section) and Jonathan S. Galatzan (Asset Forfeiture and Recovery Section) prosecuted the matter.
