A judge Tuesday tossed out 17 felony charges against a Petaluma real estate agent accused of swindling investors out of $20 million, citing the co-mingling of funds as a barrier to proving the allegations.

But Judge Shelly Averill said there was sufficient evidence to place Aldo Baccala on trial for 123 counts including grand theft, securities fraud and elder financial abuse in an alleged Ponzi scheme that targeted many retired people.

The judge said the remaining 31 charges listed in the original 164-count complaint will be dismissed because prosecutors have decided not to proceed on them.

Averill noted the changes will not make a difference in the amount of prison time Baccala could get if convicted at trial. Baccala, 72, could spend the rest of this life behind bars, with enhancements for white-collar crime and other offenses.

Averill's ruling followed weeks of testimony from investigators and alleged victims of what is believed to be one of the largest Ponzi schemes in Sonoma County history.

Baccala is accused of luring 55 investors to his various holdings on promises of double-digit returns. Instead of plugging the money into the properties, he used it to make interest payments to other investors, prosecutors said.

Some investors, who put up as much as $2 million, lost their life savings, prosecutors said.

Baccala was arrested a year ago and has been in jail ever since. His bail is $2 million.

Averill ordered him to return to court June 12 for an arraignment on the charges.

The District Attorney's Office has posted the original complaint on its website at http://da.sonoma-county.org/.