The attorney assigned to unravel a Connecticut-based investment pyramid scheme says it will take longer than expected to account for the money, including hundreds of millions of dollars invested on behalf of a pension fund for Venezuelan state oil workers.

The court-appointed receiver, John Carney, is investigating the financial dealings of Francisco Illarramendi, a Venezuelan-American accused of taking money from hedge funds he operated in Stamford, Conn., for personal use. U.S. prosecutors in Connecticut have called it the state's biggest white-collar federal prosecution.

Carney on Monday asked for a three-month deadline extension to Sept. 30, saying the task has been complicated by gaps in the paper trail and other challenges.

"The magnitude and fraudulent nature of the transactions, the lack of meaningful documentation, the involvement of foreign entities, and the sheer quantity of data all necessitate additional time," Carney, of the New York law firm Baker & Hostetler, wrote in the court filing.

The office of the U.S. district judge handling the case, Janet Bond Arterton, said the request was pending Tuesday.

Illarramendi, 42, of New Canaan, pleaded guilty on March 7 to criminal charges including several counts of fraud and conspiracy to obstruct justice. He faces up to 70 years in prison at a sentencing hearing that remains to be scheduled.