Specifically: "Ms. Biesterfeld received an evaluation following three months of her employment and received an overall rating of 5 on a scale of 10. Goals for improvement included the proper completion of the cash report, proper documentation of the collection of fines, the importance of seeking clarification of policies and procedures, developing clerical skills, working on assigned tasks and keeping her supervisors informed of all problems and community complaints. Ms. Biesterfeld failed to improve..."
"Regarding the specific incident... Ms. Biesterfeld did not tell her supervisors that the patron was accessing child pornography, and thereafter she neglected to notify anyone in management of the events which transpired, including the suspect's arrest until after they had occurred and failed to advise that the library's computer had been seized... There were additional performance deficiencies and policy violations that were discovered which led to her release."
Today's LA Times features an op-ed by Christopher D. Greene in support of Biesterfield's actions here.