According to the Los Angeles Daily Journal, the Internal Revenue Service is looking into possible tax evasion and other financial misconduct.
McCourt's attorney said McCourt and his ex-wife, Jamie, have received requests from the IRS for documents, but the ex-couple themselves are not the target of investigators.
McCourt sold the team for $2 billion earlier this year after a protracted divorce battle and placing the team in bankruptcy. In bankruptcy filings, attorneys for Major League Baseball said McCourt looted more than $180 million in revenues from the club for personal use and other business unrelated to the team.
The Associated Press contributed to this report.