Investigators are focusing on three rank-and-file workers and two administrators at the prison where the former Symbionese Liberation Army member is incarcerated, the Los Angeles Times reported Thursday. The rank-and-file workers calculate inmate release dates, the newspaper said.

Olson, who was known as Kathleen Soliah during her SLA days, was released in error March 17. She was taken back into custody less than a week later and returned to prison, after officials realized she still had at least one year of her sentence to serve.

She was sentenced to multiple prison terms for her role in a 1970s killing and a plot to bomb Los Angeles police cars. The SLA was also responsible for the kidnapping of heiress Patty Hearst.

The Los Angeles Times reported this week that two years had mistakenly been trimmed from Olson's sentence when her file was being transferred to a new record-keeping system. The union representing corrections clerks told the newspaper the new system requires better training for people who keep prisoner records.