U.S. federal prosecutors have charged Houston billionaire Robert Brockman with tax evasion in what they say is the biggest case of its kind against an American citizen.

Brockman is the chief executive officer of Ohio-based software company Reynolds and Reynolds Co.

Brockman appeared in federal court from Houston via Zoom Thursday. He was charged with seven counts of tax evasion, six counts of failing to file foreign bank account reports, 20 counts of wire fraud, two counts of concealment money laundering, two counts of tax evasion laundering and one count each of international money laundering, evidence tampering and destruction of evidence.

He entered a plea of not guilty to all counts and was released on $1 million bond, said Abraham Simmons, spokesman for the Northern District of California.

"Mr. Brockman has pleaded not guilty and we look forward to defending him against these charges," his attorney Kathryn Keneally said in an email.

Brockman is suspected of hiding $2 billion in income from tax authorities over 20 years. He is accused of using a web of offshore businesses in Bermuda and St. Kitts and Nevis - including a family charitable trust, indictment documents unsealed on Thursday showed.

Brockman was also charged over allegations of fraud involving debt securities, "breaking a promise to investors that he would not buy or sell his own company's debt," Reuters quoted U.S. Attorney David Anderson as saying.

Reynolds and Reynolds employs 4,300 staff and provides operating systems used by motor-vehicle dealerships to manage operations.

Fellow businessman Robert Smith agreed to a deal with prosecutors, Justice officials said late Thursday. Smith in 2019 promised to pay off academic loans of the entire graduating all-Black class at Morehouse College.

Prosecutors said Smith would cooperate with federal authorities and pay nearly $140 million to end tax charges. Smith - founder and chief executive officer of Vista Equity Partners - is the wealthiest African American investor in the U.S.

Smith admitted to using a corporate manager and designated trustee to his ties in four offshore companies, prosecutors said. Based on documents filed in relation to Smith's deal, he and Brockman have been business partners since the late 1990s. According to Forbes Magazine, the 57-year old Smith is worth more $5 billion.