An encrypted messenger app promoted itself as a place for “dads, uncles, and babysitters” to chat, share material, and meet up online.
Investigators allege it was a heinous place, where predators swapped graphic videos of children — many just babies or toddlers — being sexually assaulted by men.
To gain access to the group, prospective members allegedly had to upload a sexually explicit image of a naked child, younger than 13. A handwritten note with the chat group’s name had to appear in the photo or video to verify it was taken by the prospective member.
That’s where Homeland Security Investigations agents allege they found Christopher Sheerer, 35, a pediatric cardiac anesthesiologist at Boston Children’s Hospital. His phone allegedly contained sexually explicit images exchanged on the app, according to court filings related to his arrest last July. He is awaiting trial in federal court in Boston on charges of possession and distribution of child pornography and has pleaded not guilty. His attorney, William Fick, declined to comment. The hospital fired Sheerer after his arrest.
The prosecution is among a staggering number of child exploitation cases brought nationwide over the past year, including a seemingly endless stream in Massachusetts charging teachers, doctors, police officers, and public officials. In May, a Gloucester police officer was charged with receipt of child pornography after the FBI allegedly traced his IP address to a site on the dark web and found images on his phone and laptop, according to court filings.
Also in May, FBI task forces arrested more than 200 people and rescued 115 children during a five-day nationwide operation targeting people accused of child exploitation.
The cases highlight the proliferation of child sexual abuse material on the dark web and encrypted platforms. They also reflect an aggressive and coordinated global effort by law enforcement, in partnership with the National Center for Missing & Exploited Children, to crack down on offenders and rescue helpless victims.
“At the heart of this crime, for every offender we arrest, there’s a child,” said Sean Garvey, assistant special agent in charge of Homeland Security Investigations New England who oversees a group that investigates child exploitation and cybercrime.
Investigators approach cases “from a victim standpoint,” said Garvey, adding that the focus is on recovering and protecting children.
“It really is a global problem,” Garvey said. “It’s truly a borderless crime.”
Investigators are using cutting-edge technology and digital forensics to determine whether images of victims have been in circulation for years, or were recently created. Investigators have at times been successful in pinpointing specific locations where child sexual abuse material was produced and rescuing victims across the United States and abroad, according to authorities. An investigation into a Wyoming businessman suspected of paying women in the Philippines to produce live video of children being sexually abused led to the rescue in January of nine children, ages 5 months to 16, in the Philippines and five arrests, according to Wyoming media reports.
“The most important thing we do is identifying these children and making sure we can get them into a safer situation,” said Doug Humphrey, an FBI supervisory special agent who oversees Boston’s Child Exploitation-Human Trafficking Task Force. He was speaking about the bureau’s overall efforts, while not commenting on pending cases.
The FBI identified — and in some cases located — 2,634 child exploitation victims in fiscal year 2024, according to the bureau. During that time, the agency opened 6,103 child exploitation cases — which include production, receipt, and distribution of child sexual abuse material, and sextortion — and made 2,634 arrests.
Homeland Security Investigations, which is part of the Department of Homeland Security, identified — and in some cases rescued — 1,783 children in fiscal year 2024, initiated 6,939 child exploitation cases, and made 4,959 arrests, according to the agency.
Investigators cited a number of challenges in handling such cases, including the proliferation of child sexual abuse material on the dark web and encrypted apps, a spike in “sextortion” cases involving scammers — frequently located overseas — who blackmail adolescents after tricking them into sharing nude images of themselves, and the emergence of artificial intelligence that can be used to create fake images.
Last year, the National Center for Missing & Exploited Children’s CyberTipline, which receives reports of suspected child sexual exploitation from the public and electronic service providers, received 20.5 million reports, of which nearly 19.9 million involved child pornography.
More than 51,000 of the total CyberTipline reports were immediately escalated to law enforcement, in many cases because they involved a child in imminent danger, according to the tipline website.
The tipline saw a 1,325 percent increase in reports involving Generative AI from the previous year, going from 4,700 in 2023 to 67,000 reports, according to its website. Those reports involve cases in which “bad actors” use AI to create nude images from photographs of fully clothed children, according to Hayley Elizondo, program manager of the tipline’s public reports.
Kimberly Milka, an assistant special agent in charge of the FBI’s Boston office who also spoke generally and not about any pending cases, said the FBI is beginning to see a number of AI child exploitation cases around the country.
“We are preparing ourselves for it because we know it is coming,” said Milka, noting that a former middle school teacher in Louisville, Ky., was recently sentenced to 19 years in prison for distributing AI-generated sexually explicit images of children.
Humphrey said agents are in the process of “trying to use AI for good,” to sort through massive amounts of child sexual abuse material and speed up the process of trying to identify victims.
“One of the challenges is just the amount of data we have to sift through,” Milka said. She noted that cellphones are capable of more storage than before, which can slow an investigation down because it takes more time to analyze data on seized digital devices.
There aren’t enough hours in the day for investigators to handle the sheer volume of child exploitation cases, according to Garvey.
“It’s so prolific through the increase of the dark net, where offenders operate at a greater level of perceived anonymity,” Garvey said. “We have to go after the worst of the worst.”
Those targets, Garvey said, include transnational organized crime groups involved in livestreaming videos of children being sexually exploited, to customers who are miles or continents away and sometimes pay with crypto currency.
Investigators said they prioritize cases involving people who hold positions of public trust that give them access to children, repeat offenders, and those involved in producing child sexual abuse material or operating platforms where it is shared.
The average profile of a child predator used to be a white male in his 30s to mid-40s, Milka said. But not anymore.
“We see every age range now,” said Milka, including a rise in the number of female offenders. They come from every socioeconomic status and “it reaches every walk of life,” she said.
Sextortion cases have also increased since the COVID-19 pandemic, with more boys than girls being targeted, and primarily those in high school, according to the FBI.
Scammers befriend the victims online while posing as another teenager, dupe them into sharing nude images of themselves, then threaten to share the images online unless they are paid a significant amount of money. The shame of being duped and having their images shared online has led many victims to feel suicidal.
“The child needs to realize this is not the end of the world,” said Humphrey, adding that often children are afraid to tell anyone they are being blackmailed.
Victims in a number of child exploitation cases pending in federal court in Boston were not even old enough to talk when they were sexually assaulted, according to court filings.
Those arrested locally recently include Joshua DeWitte, a former music teacher at Buckingham Browne & Nichols School in Cambridge, and Christopher Allan Tisoy of Baltimore. They were charged in federal court in Boston with sexual exploitation of children. DeWitte, who is already facing related state charges, is accused of sending payments totaling nearly $24,000 to Tisoy to produce videos of boys being sexually exploited in the Philippines. He allegedly boasted during a conversation in the Telegram messaging app that he sexually assaulted boys, in the Philippines, Japan, and Korea, according to court filings. Attorneys for DeWitte and Tisoy did not respond to requests for comment.
A jury trial is slated for November in federal court in Boston for former New Hampshire state representative Stacie-Marie Laughton and her former partner, Lindsay Groves, who are accused of sexual exploitation of children. Groves is accused of taking nude photos of toddlers at the Tyngsborough day care center where she worked and sharing them with Laughton.
Lawyers for those accused, including Alexander Aiello, the Gloucester police officer, did not respond to requests for comment or declined comment.
Shelley Murphy can be reached at shelley.murphy@globe.com. Follow her @shelleymurph.