An Orange County man was sentenced to just over one year in federal prison for running an illegal sports-betting business and filing a false tax return. 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. Authorities said his bookmaking operation ran for at least five years until October 2023 and involved more than 700 bettors at times. The operation used several Costa Rica-based websites and a call center to allow agents and customers to place bets.
According to prosecutors: “[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.”
The investigation revealed that Bowyer operated his business out of various locations in Los Angeles and Orange counties as well as Las Vegas. He employed agents and sub-agents—including casino hosts—who received commissions based on bettor losses. Sometimes commissions were paid using chips from “Casino A,” where Bowyer also gambled.
One notable client was Ippei Mizuhara, former Japanese-language interpreter for MLB player Shohei Ohtani. Mizuhara is currently serving a 57-month federal prison sentence after admitting he stole nearly $17 million from Ohtani to pay off gambling debts and failed to report related income on his taxes. Between September 2021 and January 2024, Mizuhara placed more than 19,000 bets with Bowyer’s operation; during this period he had total winning bets exceeding $142 million and losing bets surpassing $182 million, resulting in about $40 million owed.
During part of this time frame—from February 2022 to January 2024—Mizuhara paid at least $16.25 million into Bowyer-controlled accounts as proceeds from illegal gambling activity. Of these funds, Bowyer directed or transferred about $9.3 million to casinos as wire payments for markers used by himself or associates.
Other clients identified include “Individual B,” a professional baseball player for a Southern California team, and “Individual C,” a former minor-league baseball player.
Prosecutors determined that Bowyer knowingly underreported his taxable income for the year 2022 by omitting over $4 million earned through illegal gambling activities—including approximately $3.8 million wired into one bank account—which resulted in owing additional taxes of more than $1.6 million.
As part of his plea agreement, Bowyer agreed to forfeit more than $250,000 in cash plus casino chips seized by law enforcement during the investigation.
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 case.
