LOS ANGELES: An elementary school teacher who worked for nearly four decades in the Los Angeles Unified School District was arrested on suspicion of sexually abusing 20 students and one adult, police said.

After a 10-month investigation, eight felony counts of continual sexual abuse and seven counts of lewd acts upon a child have been filed against Robert Pimentel of Newport Beach for abuse that took place at George De La Torre Jr. Elementary in the Wilmington area, Officer Christopher No told The Associated Press.

Besides the 15 felonies, misdemeanor charges are expected for the remaining incidents, No said.

His bail has been set at $12 million, and an arraignment date hasn't been set.

Pimentel, 57, left his fourth-grade teaching position last March when allegations arose from several girls who told their parents he inappropriately touched them during school and police opened an investigation.

District officials immediately removed him from campus and parents and state credentialing authorities were informed, school district spokesman Daryl Strickland said. Parents and guardians will be told of the arrest by letter and phone, he said.

Before the official dismissal process with the Board of Education could begin, Pimentel, who had worked for the district since 1974, retired.

"Can you go back and fire someone who's already retired? No, you can't," LAUSD Superintendent John Deasy told the Los Angeles Times.

Deasy said the school's principal was also immediately removed because the superintendent was "dissatisfied" with how the incident was handled.

Court records obtained by the Times show the allegations covered a period between Sept. 2011 to March 2012.

LAPD Capt. Fabian Lizzaraga told the newspaper Pimentel is suspected of inappropriately touching the children over and under their clothing.

The Police Department said the teacher's name was spelled "Pimental," but the school district and public records give the spelling as "Pimentel."

Police did not know if he had hired an attorney. A woman who picked up the phone at a number listed for Pimentel hung up when asked about a lawyer or comment from family.

There have been several high-profile recent cases of Los Angeles teachers accused of sexually abusing students. More than 225 parents and students are involved in various claims for damages against the district after Miramonte Elementary School teacher Mark Berndt was arrested a year ago and has pleaded not guilty to 23 counts of lewd conduct.

In December, a jury ordered the district to pay a boy molested by an elementary school teacher $6.9 million - among the largest awards in the history of the school system.

The jury found the district liable for the repeated molestation of the 10-year-old student in 2008 and 2009 by teacher Forrest Stobbe at Queen Anne Elementary School in the city's mid-Wilshire district.