An investment advisor who stands accused by the Securities and Exchange Commission of stealing about $53 million from a hedge fund he managed is now facing additional charges of using other funds to run a Ponzi scheme.

Connecticut-based hedge fund manager Francisco Illarramendi, 49, plead guilty to fraud today in a U.S. District Court in Bridgeport, Conn.

The agency has filed additional charges against Illarramendi and his firm, MK Capital, alleging they misused two hedge funds for Ponzi-like activities. Two other men, Juan Carlos Guillen Zerpa, 43 and Juan Carlos Horna Napolitano, 40, were also charged in the scheme. The SEC further alleges that the trio attempted to hide his hedge funds' missing assets by giving the SEC a letter from a Venezuelan accountant that falsely claimed one of the funds held $275 million.

"Illarramendi knew that the SEC was onto his scheme and compounded his fraud by attempting to mislead the Commission's staff," said David P. Bergers, Director of the SEC's Boston Regional Office.

In a parallel action, the U.S. Attorney's Office of the District of Connecticut unsealed criminal charges against Illarramendi for the same actions, as well as for obstruction of justice for deliberately misleading the SEC staff's investigation.

The SEC originally filed charges against Illarramendi in January, alleging that in 2009 he transferred about $53 million in investor funds into his own bank accounts and used the money for personal investments. The SEC has obtained a court order freezing the assets of Illarramendi and his firms.

"Illarramendi treated his clients' money like it was his own, diverting millions of dollars that did not belong to him," said Bergers. "He abused his position of trust with his clients and breached his responsibilities as an investment advisor."

Illarramendi is the majority owner of MK Group-a holding company for investment advisor MK Capital Management LLC, which manages several hedge funds containing up to $540 million in assets, according to the SEC. MK Capital is not registered with the SEC.

Bloomberg News contributed to this article.