(CNN) -- A former member of the radical 1970s group Symbionese Liberation Army is back in custody after a clerical error miscalculated her prison release date, a California Department of Corrections spokesman said Saturday.

Sara Jane Olson wipes away a tear at a Los Angeles courthouse in 1999.

Sara Jane Olson was freed Monday.

But her earliest release date is now March 17, 2009, Chief Deputy Secretary Scott Kernan said, calling the error "an aberration."

"Our department immediately rearrested her, and she will serve her full sentence," Kernan said.

He described Olson as cooperative and said the arrest took place "without incident."

She will serve the year at the Central California Women's Facility in Chowchilla, California.

"The department is sensitive to the impact such an error has had on all involved in this case and sincerely regrets the mistake," Kernan said. Watch explanation for mistaken release »

An investigation is under way to find out how the error happened, he added.

Olson had served about six years behind bars for her role in incidents in 1975: the attempted bombing of two police cars and the shooting death of a customer during a bank robbery.

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Prosecutors said she was part of an SLA plot to murder Los Angeles police officers by planting bombs under their squad cars.

One of the cars was parked outside a crowded Hollywood restaurant. The bombs did not go off, and no one was hurt.

The SLA is best known for its 1974 kidnapping of newspaper heiress Patty Hearst.

A parole board hearing in 2004 reduced the sentence related to the attempted bombing charge, but "an administrative error failed to take into account" the second-degree murder charge for the shooting death, Kernan said.

David Nickerson, one of Olson's attorneys, said he and co-counsel Shawn Chapman Holley intend to file a petition with Los Angeles Superior Court on Monday.

Olson cannot be treated as "yo-yo" in regard to the law, he said.

Chapman Holley called her return to custody "ridiculous." "It's like they make up all new rules when it comes to her," Chapman Holley told The Associated Press. "It's like we are in some kind of fascist state."

The administrative error was verified late Saturday morning, Kernan said, after a thorough review of Olson's case. He said "concerns" about her release date prompted the review.

Olson was taken into custody at Los Angeles International Airport on Friday night, Kernan said.

Olson had been granted interstate parole and was on her way to Minnesota, where she lived for more than two decades as a fugitive before she was arrested in 1999, Nickerson had said.

From the Los Angeles airport, authorities took Olson to her home in Palmdale, California, where she remained until she was arrested midday Saturday, when the review was completed, Kernan said.

Originally named Kathleen Soliah, Olson fled California after authorities began looking for her and then changed her name and lived for more than two decades as a fugitive before she was arrested in 1999 in Minnesota.

She had married and was raising three daughters.

Many residents rallied to Olson's cause and helped post bail for her.

But one group in California, the Los Angeles Police Protective League, denounced her release.

"She needs to serve her full time in prison for these crimes and does not deserve time off for working in prison," the group said.

"After participating in one killing and attempting two more, she managed to elude authorities and live a guilt-free middle class life for decades. Criminals who attempt to murder police officers should not be able to escape justice simply because they have good lawyers." E-mail to a friend

CNN's Irving Last contributed to this report.

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