A one-time Petaluma real estate agent charged with defrauding dozens of investors out of $20 million admitted his role Wednesday in a plea deal that will limit his prison time to about eight years.

Aldo Baccala, 73, was facing life in prison for running one of the largest Ponzi schemes in Sonoma County history. He was expected to go to trial later this month on 140 felonies including securities fraud, grand theft, elder financial abuse and white-collar crime.

But Baccala accepted an offer from Judge Gary Medvigy to serve no more than a decade in exchange for his plea to all charges. With credit for time already served, he could be released when he's 81.

Medvigy cited Baccala's age and lack of a record in extending the lighter sentence. As the judge read down the long list of charges, each with a named victim, the gray-haired Baccala uttered a barely audible, "No contest, your honor."

Prosecutors opposed the deal, saying Baccala's scam was devastating to his 55 victims, many of whom lost their retirement savings. They are expected to share their stories at Baccala's June 3 sentencing.

"I think it should be more time," said Ron Smetana, a prosecutor from the state Attorney General's Office who assisted with the case. "I don't know what that number is. But $20 million is a lot of money."

Baccala's lawyer, Lynne Stark-Slater, said her client never meant to defraud anyone. She said the failed investments coincided with the 2008 economic downturn.

But she said he accepted responsibility because the risk of a long prison term was too great. And he attempted to make good on his obligations by surrendering his assets early on, she said.

Under the agreement, he pleaded to crimes occurring from 2004 to 2008. Investors during that time wrote him checks for up to $2 million on the promise of earning double-digit interest on projects ranging from nursing homes to a car wash.

Baccala didn't tell them, however, that he was deeply in debt over his recent stock market losses. He began using new loans to pay off old ones until he could no longer keep the deception going.

"This guy got in a treadmill that kept going faster," Smetana said.

Baccala notified investors of the dire situation in 2008, when he suspended monthly payments. They sued, winning a $21 million judgment.

State and local authorities launched a criminal investigation and Baccala was arrested in 2012. He has remained in custody ever since.

Smetana estimated some of the investors could expect to get back up to a quarter of their money. But many others lost homes or went bankrupt and are now destitute, he said.

You can reach Staff Writer Paul Payne at 568-5312 or paul.payne@pressdemocrat.com