Peregrine Financial Group Chief Executive Russell Wasendorf Sr. pleaded guilty in an Iowa courtroom Monday to embezzling more than $100 million from customers of his futures brokerage, lying to regulators to cover his tracks, and mail fraud.

Wasendorf, 64, agreed to plead guilty to the charges earlier this month after confessing in July to stealing from clients for nearly 20 years.

Wasendorf, who has been in jail since being arrested in July for lying to regulators, will remain behind bars while a judge assesses whether he is a flight risk. He previously had been set to be released after the hearing Monday, but prosecutors argued he should stay in jail.

In a small courtroom in Cedar Rapids, Iowa, Magistrate Judge Jon Scoles confirmed that Wasendorf wanted to plead guilty to each of four charges.

"Are you pleading guilty because you are guilty?" Scoles asked the former futures-industry executive, who was wearing an orange prison jumpsuit and shackled at the wrists and ankles.

"Yes, your honor," Wasendorf replied.

Prosecutors said in court that Wasendorf, who faces up to 50 years in prison, should spend the rest of his life behind bars. Wasendorf's public defender argued for a sentence of about 24 to 30 years, which could be a life sentence given his age.

A date for his sentencing was not set.

Wasendorf attempted to kill himself on July 9 near the headquarters of his Cedar Falls, Iowa, brokerage. He was arrested on July 13 and charged with 31 counts of lying to federal regulators.

The search continues for the money he stole. Former clients are still unable to access funds frozen since the firm's bankruptcy on July 10.

Wasendorf previously was expected to be released from the Linn County Jail in Iowa, where he has been held in isolation and under suicide watch since his arrest, after he pleaded guilty on Monday.

In approving the release last week, Scoles said Wasendorf's chances to flee were limited because he had surrendered his passport and assets to authorities.

However, prosecutors on Monday objected to the plan and Chief Judge Linda Reade of the U.S. District Court of the Northern District of Iowa ruled that Wasendorf "shall remain detained pending further order of the court," according to a court filing.

A date for the next order was not released.

The public defender representing Wasendorf has declined to comment.