Published: Jul 21, 2011 10:54 PM EDT
Updated: Jul 21, 2011 9:53 PM EDT

COLLIER COUNTY, Fla. - Robert Alter, the Collier County school volunteer charged with molesting children changed his plea to guilty Thursday.

In court, 61-year-old Alter pleaded guilty to 23 counts of molestation.

He was arrested in January after nine girls under the age of 12 came forward with accusations he sexually abused them at two Immokalee elementary schools.

He avoided a mandatory life sentence by changing his plea. Instead, he will get 30 years in prison.