Authorities announced a 119-count indictment against Carlos Deangelo Bell, 30, of Waldorf, on Monday.
Investigators have so far determined that there are 24 victims, 11 of whom have yet to be identified, Charles County States Attorney Tony Covington said.
The allegations against Bell include 12 counts of child sexual abuse, 44 counts of filming child pornography, 38 counts of second-degree sex offenses, and three counts of transmitting or attempting to transmit HIV virus to another person.
"These charges are horrific and I share in the disgust and outrage that our community is feeling," Charles County Public Schools Superintendent Kimberly Hill said in a letter to parents, posted on the school system's webpage.
Bell's attorney, Jeffrey Griffith, said Bell, who is being held without bond, is looking forward to fighting the allegations.
Bell was initially arrested in late June and charged with three counts of producing child pornography and two counts of second-degree assault.
Authorities said at that time that Bell, a former instructional assistant at Benjamin Stoddert Middle School, molested at least seven boys on school property, at his home and possibly at other locations. Sheriff Troy Berry said the evidence included images of Bell, who admitted that he is HIV-positive, assaulting the victims.
School officials said Monday that Stoddert's school principal, Kenneth Schroeck, has been reassigned.
They also are reviewing all of their policies and procedures, but said that at the time of his hiring, Bell had not been listed on any sex abuser registry and had no criminal record.
School district officials say Bell was hired in October 2014, after a criminal background check, as a temporary instructional assistant assigned to J.P. Ryon Elementary School. In March 2015, he was hired as an instructional assistant and assigned to Stoddert Middle School.
After serving as indoor track coach for Maurice J. McDonough High School's team during the 2015-2016 school year, Bell was hired in November 2016 as the indoor track coach at La Plata High School, according to school system officials.
Law enforcement officials, meanwhile, have said Bell worked in 2015 for AlphaBest, a Charles County government contractor providing before- and after-school care at Ryon Elementary and William B. Wade Elementary School. Investigators say that in the spring of 2016, Bell volunteered as an assistant coach for a Waldorf community track club, the Comets, whose members ranged in age from 15 to 18 years old.
The Charles County Sheriff's Office notified school district officials in December that Bell was under investigation after a La Plata parent complained about inappropriate electronic messages Bell sent to a student on the track team. Bell was placed on administrative leave that month, and later fired after failing to show up for a temporary assignment in a print shop.
Hill, the school superintendent, issued a no-trespass order against Bell in May after hearing that he was seen at a track event the day before.
Copyright 2018 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.