LOS ANGELES (AP) — Former SLA fugitive Sara Jane Olson, who tried to withdraw the guilty plea that sent her to prison, has filed notice she will appeal it to a higher court.

Olson's lawyer, Shawn Snider Chapman, filed the notice in the same Superior Court where Olson was sentenced to 20 years to life in prison last month for plotting to blow up a pair of Los Angeles police cars in the 1970s.

A copy of the notice, filed Tuesday, was obtained Friday by The Associated Press. Chapman did not immediately return phone calls seeking comment.

The day before her sentencing, Olson and four former members of the Symbionese Liberation Army were charged with first degree murder in the killing of a woman during a Sacramento area bank robbery in 1975.

Olson's appeal, of a charge to which she already has admitted guilt, is an unusual procedure. The request for a certificate of probable cause notes that the courts do not allow appeals from guilty pleas unless special provisions are met. One of those is the issuance of a "certificate of probable cause" by the trial court.

Chapman's motion said the law requires the defendant to show that the appeal is not frivolous and is based on "reasonable constitutional, jurisdictional or other grounds."

"Olson will contend on appeal that the court erred in denying her motion to withdraw her guilty pleas," reads the motion. It noted that she has contended her plea was coerced by a former attorney.

Olson also said she is trying to withdraw her plea because she is innocent.

The motions were addressed to Superior Court Judge Larry Fidler, who previously refused to allow the plea withdrawal and sentenced Olson.

Olson, who was a fugitive for more than 20 years, was captured in Minnesota in 1999, where she was living with her husband and three children in an upscale St. Paul neighborhood.