Following a complex and lengthy investigation at Newtown High School that started last May, police have arrested three students and have referred 20 other students to a community-based juvenile review board concerning their use of mobile computer networks to transmit and receive sexually explicit images and videos among themselves, commonly known as sexting.

All students either arrested or referred to the review board were under age 18 when the violations occurred, so police did not disclose their identities.

The three male students who were arrested this week each were charged with one count of obscenity as to minors, obscenity, transmission/possession of child pornography by a minor, and possession of child pornography, police said. Those three boys are scheduled for appearances in Danbury Juvenile Court. Such court sessions are held in closed session and are not open to the public.

Two of the four criminal charges are felonies and two are misdemeanors.

Sergeant Aaron Bahamonde, a police spokesman, said the school system has conducted its own investigation of the case and has disciplined the students who were involved in the illicit activity.

School Superintendent Dr Joseph V. Erardi, Jr, said that whenever school administrators learn of adverse situations involving students outside of Newtown High School, it becomes a concern of school administrators.

The intensive investigations conducted by school officials and by police revealed activities that are not acceptable behavior, he said.

Dr Erardi said that he was pleased that in nearly all cases, when questioned, the students who were interviewed by officials were honest.

He termed the outcome of the investigations "a very difficult lesson that has been learned," adding that he expects that such behavior will not occur again.

There is now a clear understanding of what is acceptable behavior, he said.

NHS Principal Lorrie Rodrigue said that school officials work in tandem with police in investigating such situations.

In the course of the school's investigation, the high school's assistant principals interviewed more than 100 students to learn what had occurred, the large majority of whom were not implicated in the case, she said.

When school discipline was given to the involved students, the degree of discipline was based on the extent of their illicit activity, she said.

In view of what occurred, the school system now includes information at its freshman assemblies on the responsible use of social media by students, Dr Rodrigue said. The schools must teach students about the responsible use of technology, she said.

In a statement, police said, "During the investigation into the circulation of these sexually explicit images and videos, the Newtown police discovered that a number of students were selling these images and videos for a monetary profit."

Police said that in May 2015, Liam Seabrook, who is the police department's NHS school resource officer, began the investigation based on allegations of student wrongdoing.

"It was discovered that numerous juvenile students [both male and female] created sexually explicit images and videos of themselves, which originally occurred outside of school, but [the matter] was brought to the attention of school administrators," police said. The administrators then alerted police about the situation, police said.

The illicit images were transmitted among high school students using mobile computer applications such as Snapchat, Facetime, iMessage, KiK, and other applications, police said.

"These images and videos were saved and subsequently circulated to other third-party juvenile students, other than the original intended recipient," police said.

During the investigation, police and school officials held numerous interviews with students and their parents, police said.

Police took several sworn written statements, seized numerous cellphones, and executed several search-and-seizure warrants.

The police investigation involved more than 50 NHS students, including witnesses and students who were later determined to not be involved in the illicit activity, police said.

Police explained that the community-based Juvenile Review Board is a diversionary program that allows community leaders to take a tempered response to what would normally be considered criminal activity by juveniles.

Such a review board, in effect, keeps the offender out of the state's criminal justice system.

Typically, such review boards impose consequences such as community service. When such a case is resolved, there is no state criminal record.

Failure to comply with review board requirements results in the juvenile offenders being arrested by police and then sent to juvenile court for the adjudication of their cases.