LOS ANGELES — Police officers and FBI agents are expected to take the stand Wednesday during pretrial hearings in the case of Sara Jane Olson, the Minnesota mother accused of helping a radical group plant bombs in 1975.

The law enforcement officers are to testify about searches they conducted more than two decades ago of properties linked to the Symbionese Liberation Army, the violent leftists who kidnapped newspaper heiress Patty Hearst.

Lawyers for Olson, who prosecutors say was an SLA soldier, claim many of the searches were illegal and want evidence, including guns, bombs and explosive material, kept out of her murder conspiracy trial, slated to begin next month.

Judge Larry Fidler may also take up the issue of jury selection. Currently, court officials are screening potential jurors to find those who could sit on a panel for six to nine months, the estimated length of the trial. The judge wants to assemble a pool of 150 time-qualified prospective jurors before selection, which will include a questionnaire on the case, begins in earnest. After a little more than two weeks of prescreening, officials are less than halfway to a pool of 150.

Olson, 54, faces life in prison if convicted. Prosecutors allege that in August 1975, when she was known as Kathleen Soliah, she plotted to plant pipe bombs under police cruisers in Los Angeles. The bombs did not detonate and no one was injured. She was a fugitive for 24 years before the FBI tracked her to St. Paul, Minn., where she had built a new life as a suburban mother and community activist.