Story highlights Carlos Deangelo Bell also faces federal charges

The plea deal helps avoid a trial where victims might have testified

(CNN) An HIV-positive former Maryland school aide and track coach pleaded guilty Friday to sexually abusing students and filming child pornography, prosecutors said.

Carlos Deangelo Bell, 30, of Waldorf, signed a plea agreement admitting guilt on 27 counts, including sexual abuse of a minor, porn charges and attempted transmission of HIV, the state's attorney for Charles County, Tony Covington, said.

"You really can't imagine what had to be gone through when investigating this case," he said, alluding to the hours of video in the case that "nobody ever wants to see."

Covington said one of his goals was maintaining the privacy and anonymity of the victims in the case, something made easier by avoiding a trial that would have been open to the public.

The charges cover conduct that spanned from May 2015 to June 2017, and the 42 victims range from 11 to 17 years old, Covington said.

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