It's a simple question that many people, especially parents, are asking. They're wondering how teachers with a seeming penchant for child abuse could get and keep jobs for years, or even decades.
And sometimes the scenario can be even worse than what happened at Miramonte Elementary School, where two teachers have been arrested on suspicion of commiting lewd acts involving nearly two dozen students.
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A case in point occurred in 1997. A high school teacher in the Sacramento area was murdered. Her throat was cut. Her assailant was a custodian at the high school, who had just been hired.
The school district put him on the payroll, while they were still waiting for results on his criminal background check. It turned out he had been convicted of manslaughter. He was on parole and had used makeup during his initial interview, to cover up a tattoo on his forehead indicating his membership in a Los Angeles street gang.
That case changed the way California schools conduct background checks for faculty, staff and administrators.
At the time, Los Angeles Unified School District officials discovered about 50 of the district's employees had criminal backgrounds. Some of their crimes were very serious, including assault.
School officials say background checks are far more extensive today. A so-called "live scan" fingerprint is required for any applicant seeking a teaching credential.
The process is repeated when a credentialed teacher applies for a job. It is the same process for any staff member or administrator. The State Department of Justice then reviews the fingerprint and sends a printout of any criminal arrests or convictions back to the school district. The FBI is notified to see if there are any convictions from other states.
If it turns out the applicant was prosecuted and convicted of a serious or violent felony, they are not eligible for employment.
LAUSD Superintendent John Deasy says the process that is now n place works. He said the temporary staff at Miramonte has been subjected to that process, and he believes it is effective.
"They are also people who have gone through our very rigorous screening process," said Deasy.
But some parents are not so sure. And the Miramonte case has made many of them wonder if there are too many potential problems with any screening process to be completely sure their kids are safe.
"There has to be periodic screening," said parent Leo Delgado. "I don't know if it's every couple of years, I don't know if it's every couple of months. But there has to be better screening."