Teacher preyed on 20 girls, ‘fantasized’ about sex acts with MA student, feds say
A former Boston teacher would have sexual conversations with underage girls over Discord while he was at school and “frequently fantasized about having sex” with one student who attended the school where he most recently taught, federal prosecutors said.
John Magee Gavin, 35, of Brookline, messaged at least 20 minors from Canada, the U.K. and across the U.S. — including Florida, Georgia, North Carolina, Tennessee, Texas, and West Virginia — and initiated sexual conversations, according to prosecutors.
Some of the girls he is accused of preying on were as young as 12, the U.S. Attorney’s Office for the District of Massachusetts said in a July 18 news release.
Gavin was also found to have 147 files of child sexual abuse material on his iPhone, including 53 videos and 94 photos of girls and boys ages 5 to 17, according to prosecutors. Court documents say some of the images showed young girls “being raped by an adult male.”
Gavin taught science at the Josiah Quincy Upper School, a school for grades 6-12, prosecutors said. Before that job, he taught sixth grade at the Academy of the Pacific Rim Charter Public School in Hyde Park. He also worked as a paraprofessional for Brookline Public Schools, according to prosecutors.
Gavin is facing one count of coercion and enticement of a minor; one count of receipt of child pornography; and one count of possession of child pornography, according to the U.S. Attorney’s Office. He was indicted July 10, when prosecutors said he was detained on related state charges.
His defense attorneys did not immediately return McClatchy News’ request for comment July 21.
Gavin had his initial court appearance and arraignment on July 21, records show. He has pleaded not guilty to the charges against him.
The Discord chats
In January, investigators linked Gavin to the Discord account that had been sending sexual messages to 20 different minors, according to prosecutors. The next month, state authorities arrested him on charges including enticing a child under 16 and possession of child pornography.
The Discord chats typically began with Gavin and the minors exchanging their ages and Gavin revealing he was a teacher, prosecutors wrote in federal court filings.
“The messages within the chats are largely sexual in nature with Gavin often asking sexually charged questions to the MVTs ... and requests for CSAM,” a July 18 motion in support of Gavin’s pretrial detention says.
The chats also showed Gavin “allegedly engaged in online masturbation sessions with the minors” and “included conversations in which Gavin expressed his sexual interest in certain students at Josiah Quincy,” prosecutors said.
Gavin’s messages with one minor showed he was sexually interested in one female freshman student at the school in particular, according to prosecutors.
On Feb. 7, Boston police executed a search warrant at Gavin’s home and seized several pieces of his clothes, along with other items considered evidence, court documents say.
Gavin lives about a “quarter mile from a playground” in Brookline, which is about a 5-mile drive southwest from Boston.
Gavin was seen wearing the clothing, including a sleeveless shirt he wore for a race, in several photos he sent to victims, according to prosecutors.
Two photos were likely taken while he was at a school, prosecutors wrote in the motion for his detention.
Detention ordered
In the motion, prosecutors argued Gavin is a serious flight risk, a “danger to the community” and that the amount of evidence against him is “overwhelming.”
“Gavin worked with children on a daily basis and was able to conceal his sexual interest in his students from his employer and the community,” the filing says. “Additionally, the nature of Gavin’s offenses is particularly disturbing considering his career as an education professional.”
The Boston Herald reports Boston Public Schools immediately put Gavin on administrative leave earlier this year.
During Gavin’s July 21 court appearance, a federal judge granted prosecutors’ motion and ordered Gavin’s detention, records show.
If convicted on the charge of coercion and enticement of a minor, Gavin would face at least 10 years in prison and up to life in prison, according to the U.S. Attorney’s Office.
He would face a minimum sentence of five years in prison and up to 20 years if convicted of receipt of child pornography, prosecutors said. If he is convicted of possessing child pornography, he would face a maximum sentence of 20 years.
Concerns or suspicions about child sexual exploitation can be reported to the National Center for Missing and Exploited Children’s CyberTipline online or by calling 1-800-843-5678.
This story was originally published July 21, 2025 at 1:58 PM with the headline "Teacher preyed on 20 girls, ‘fantasized’ about sex acts with MA student, feds say."
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