A former science teacher at a Boston school is facing more consequences as a result of his alleged attraction to minors, evidenced by what authorities describe as a large collection of files depicting child sexual abuse material.

A federal grand jury has indicted John Magee Gavin, 35, of Brookline, for allegedly coercing or enticing at least one underage female to engage in sexual conversations online and requesting that she produce and share explicit material of herself.

The former teacher at the Josiah Quincy Upper School has been in state custody on related charges since February, when Brookline Police arrested the man at his residence.

Gavin is slated to appear in Boston federal court Monday morning. He has been indicted on one count each of coercion and enticement of a minor, receipt of child pornography, and possession of child pornography.

Gavin’s alleged fascination with messaging minors came to an end in January, when authorities identified him as the owner of a Discord account who had communicated with at least 20 underage females between the ages of 12 and 17 located across the country, and in the United Kingdom and Canada.

“It is alleged that, in these chats, Gavin disclosed that he was a teacher, engaged in sexual conversations and often asked the minors to send him pictures of themselves engaged in sexually explicit conduct – knowing that the children were underage,” according to a release from Massachusetts US Attorney Leah Foley’s Office.

In a memorandum filed in federal court, supporting the prosecution’s request for pretrial detention, Assistant US Attorney Luke A. Goldworm highlights how Brookline Police seized several items of clothing that matched the attire Gavin was seen wearing in photos the teacher sent to his victims.

Last month, federal agents completed a review of Gavin’s iPhone that contained 147 files depicting child sexual abuse material – 94 images and 53 videos. It is alleged that the content shows the rape of both female and male minors, ranging in age from approximately five to 17 years old.

Agents allegedly found that Gavin’s Discord account revealed the teacher engaging in numerous chats with minors that included “online masturbation sessions” and “sexualized conversations with the minors while he was at school,” according to Foley’s office.

“The chats also allegedly included conversations in which Gavin expressed his sexual interest in certain students at Josiah Quincy,” the office stated. “In one conversation, Gavin allegedly discussed his sexual interest in a freshman student at the school where he was employed as a teacher and fantasized about having sex with her.”

Boston Public Schools took action against Gavin immediately, placing the teacher on administrative leave. The district, in February, pointed out that the state charges were not related to BPS or BPS students.

Gavin previously worked at the Roland Hayes School in Brookline as a paraprofessional in 2020, from January through August of that year, according to authorities.

The Academy of the Pacific Rim Charter Public School in Hyde Park hired Gavin as a teacher in August 2022, passing all of the school’s background checks, Executive Director Farida Mama Graham wrote in a letter to families in February.

The school’s records “also show that no complaints were ever filed by parents, students or staff against this teacher during his time of employment,” Graham added. Gavin resigned last August before taking his position at Josiah Quincy School.

Gavin remains in state custody. If released, he will face a slew of conditions that include being placed on GPS with an exclusion zone of the Josiah Quincy School and required to stay away and have no contact with the victims, and no contact/communication with children under age 18.

He would also be required to surrender his passport and not be allowed to leave Massachusetts, while not using social media or applications that allow for texting such as Discord, WhatsApp, Snapchat, and TikTok.

“His pretrial release would endanger his former students who he has demonstrated a sexual interest in,” Assistant US Attorney Goldworm stated in his request for pretrial detention. “There is a serious risk that Gavin could use his relationship with the students or the knowledge he has learned about them to arrange a meetup or contact these students.”

Josiah Quincy Upper School. (Nancy Lane/Boston Herald)