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According to the report, Mickelson is not being investigated and has not been charged in the case.
The case against Silveira revolves around a $2.75 million wire transfer he received from a "gambling client" and was to be used for "illegal sports betting."
Mickelson is not named in the court documents. However, the two sources for "Outside the Lines" identified Mickelson as the unnamed "gambling client." Also, an initial plea agreement referred to "money laundering of funds from P.M."
According to the ESPN report, Mickelson has a history of sports gambling, with sources telling "Outside the Lines" that Mickelson has "won far larger sums betting on major sporting events like the Super Bowl" and that "Mickelson still bets on sports in Vegas."
Silveira is facing up to 60 years in prison but is expected to be sentenced to far less.
Mickelson's publicist declined to comment on the report when contacted by Business Insider. One of Mickelson's attorneys declined to comment in the ESPN report.