A California couple, owners of a Benicia-based solar energy company, pleaded guilty in federal court on Friday to participating in a $1 billion dollar Ponzi scheme—the biggest criminal fraud scheme in the history of the Eastern District of California, according to a release from the U.S. Attorney’s Office.

Jeff Carpoff, 49, of Martinez, pleaded guilty to conspiracy to commit wire fraud and money laundering. His wife, Paulette Carpoff, 46, pleaded guilty to conspiracy to commit an offense against the U.S. and money laundering.

Also on Friday, in a parallel case, the couple settled a civil case with the Securities and Exchange Commission. They have consented to permanent injunctions, with monetary relief to be determined by the court at a later date, the SEC said.

According to the complaint, between 2011 and 2018, the Carpoffs offered and sold investment opportunities through two solar energy companies, DC Solar and DC Solar Distribution Inc., in the business of making, leasing and operating mobile solar generators. The solar generators were mounted on trailers that were promoted as being able to provide emergency power to cell phone towers and lighting at sporting events.

The Carpoffs and others, the complaint said, claimed these investment opportunities would deliver gains in the form of tax benefits, guaranteed lease payments and the resulting profits from the operation of the generators.

But in reality, thousands of the purportedly profitable generators were never manufactured, let alone put into use, and the vast majority of alleged “revenue” sent to investors came from investor money, not from actual lease payments from end-users of the generators, the complaint said.

DC Solar, the complaint said, solicited investors directly and indirectly through brokers and salespeople using various methods, including e-mail, conference calls and in-person meetings. The complaint noted that DC Solar offered and sold investment fund contracts and sale-leaseback contracts through interstate commerce to investors throughout the U.S.

The company raised approximately $910 million in investor money over the course of the offerings, the complaint said, noting that these deals had face values of more than $2.7 billion because investors in the investment fund contracts financed approximately 70% of the amount of their investments through promissory notes.

The complaint said the couple used at least $140 million of investor money to fund their lavish lifestyle, which included 150 luxury and sports cars, dozens of properties and a share in a private jet service.

U.S. Attorney McGregor Scott said this case represents not only the largest criminal fraud scheme in the history of the district, it also represents the largest criminal forfeiture in the history of the district, with more than $120 million in assets forfeited. All of the money will be returned to the victims, he said, adding that the scheme also targeted the U.S. Treasury, which had $500 million returned. Investigators and attorneys from various federal agencies are still working to return money to victims and the Treasury department.

The Carpoffs are scheduled to be sentenced on May 19. Jeff Carpoff faces a maximum statutory penalty of 30 years in prison. Paulette Carpoff faces a maximum statutory penalty of 15 years in prison.

In addition, prosecutors said four defendants have previously pleaded guilty to federal criminal charges related to the fraud scheme since October. Joseph W. Bayliss, 44, of Martinez, and Ronald J. Roach, of Walnut Creek, each pleaded guilty to related charges on October 22, 2019. Robert A. Karmann, 53, of Clayton, pleaded guilty to related charges on December 17, 2019. Ryan Guidry, 53, of Pleasant Hill, pleaded guilty to related charges on January 14, 2020. A seventh co-conspirator is scheduled to plead guilty on February 11.

The investigation into the fraud remains ongoing.