NORWOOD, Colo. — At the state high-school wrestling tournament in Denver last year, three upperclassmen cornered a 13-year-old boy on an empty school bus, bound him with duct tape and sodomized him with a pencil.

For the boy and his family, that was only the beginning.

The students were from Norwood, Colo., a ranching town of about 500 people near the Telluride ski resort. Two of the attackers were sons of Robert Harris, the wrestling coach, who was president of the school board. The victim’s father was the K-12 principal.

After the principal reported the incident to police, townspeople forced him to resign. Students protested against the victim at school, put “Go to Hell” stickers on his locker and wore T-shirts that supported the perpetrators. The attackers later pleaded guilty to misdemeanor charges, according to the Denver district attorney’s office.

“Nobody would help us,” said the victim’s father, who asked not to be named to protect his son’s privacy. Bloomberg News doesn’t identify victims of sexual assault. “We contacted everybody and nobody would help us,” he said.

High-school hazing and bullying used to involve name- calling, towel-snapping and stuffing boys into lockers. Now, boys sexually abusing other boys is part of the ritual. More than 40 high school boys were sodomized with foreign objects by their teammates in over a dozen alleged incidents reported in the past year, compared with about three incidents a decade ago, according to a Bloomberg review of court documents and news accounts.

Among them, boys were raped with a broken flagpole outside Los Angeles; a metal concrete-reinforcing bar in Fontana, Calif.; a jump-rope handle in Greenfield, Iowa; and a water bottle in Hardin, Mo., according to court rulings and prosecutors.

At New York’s elite Bronx High School of Science, three teenage track-team members were arrested after a freshman teammate alleged they repeatedly hazed him between December and February, including holding the boy down and sodomizing him with their fingers. They pleaded not guilty in New York state criminal court in the Bronx, according to Melvin Hernandez, a spokesman for the Bronx District Attorney’s office. A lawyer for one of the boys was unavailable for comment; the other two declined to comment.

While little research has been done on boy-on-boy sexual hazing, almost 10 percent of high school males reported being victims of rape, forced oral sex or other forms of sexual assault by their peers, according to a 2009 study in the Journal of Youth and Adolescence.

“This is right out of ‘Lord of the Flies,”‘ said Susan Stuart, a professor of education law at Valparaiso University Law School in Indiana, who has studied an increase in federal lawsuits brought by male victims of sexual hazing. “And nobody knows about it.”

Hazing in high school is fueling college hazing, experts say, as a new generation of players on middle- and high-school sports teams learn ways to haze through social media, said Susan Lipkins, a psychologist in Port Washington, N.Y., who has studied the subject for 25 years. The practice has been increasing in frequency over the past decade, becoming more brutal and sexually violent, she said.

“Each time a hazing occurs, the perpetrators add their own mark to it by increasing the pain or humiliation,” Lipkins said.

High school boys are trying to prove their masculinity to each other by humiliating younger boys because that’s what they think manliness is all about, said William Pollack, associate professor of psychology at Harvard Medical School.

“We keep saying to the boy: ‘Be a man,’ and a boy is not a man, so that’s not possible,” said Pollack, who is also director of the Centers for Men and Young Men at McLean Hospital in Belmont, Mass.

In at least four cases of sodomy hazing last year, the coach or supervising teacher was alleged to have known about it, ordered it, witnessed it or laughed about it, according to police reports and court filings.

At Maine West High School in Des Plaines, Ill., a Chicago suburb, varsity soccer players allegedly “rewarded” new teammates by holding them down and sodomizing them with sticks and their fingers, while coaches did nothing to intervene, according to court documents and police reports.

After witnessing an attack on a 16-year-old in July, varsity coach Michael DiVincenzo allegedly congratulated the victim and asked him “if it was all good,” according to a police report. During a freshman drill, he was alleged to have told players they would be sodomized by the varsity team if they failed to communicate effectively, according to a police report.

DiVincenzo was arrested last month on misdemeanor charges of hazing, battery and failure to report child abuse, Cook County State’s Attorney Anita Alvarez in Chicago said in a statement. He was released on cash bond and hasn’t entered a plea. Charges against varsity players were dropped at the request of the victims’ families, Alvarez said.

DiVincenzo’s attorney, Thomas Breen, didn’t respond to phone messages or email requests for comment. In April, DiVincenzo issued a statement denying “guilt of any kind.” In a police interview, he denied knowledge of the alleged attacks.

Maine West, whose board voted to fire DiVincenzo, has cooperated fully with the investigation and hired a former U.S. attorney who cleared the district’s handling of the matter, said David Beery, a spokesman. The school has also instituted more training for staff and set up an anonymous Web-based tip line for students to report hazing.

About 4,000 sexual assaults occur each year inside U.S. public schools, as well as 800 rapes or attempted rapes, according to a letter the U.S. Education Department sent to educators in April 2011.

“We don’t tolerate this anywhere else in our society,” said Antonio Romanucci, a Chicago attorney representing some of the alleged Maine West victims in a civil lawsuit. “So why are we tolerating it in our schools?”

State anti-hazing laws enacted in the 1990s have had little effect as victims are often reluctant to testify and penalties are mild. While the Education Department hasn’t warned schools about sexual hazing, it has offered guidance on bullying, cautioning schools that they can be held liable for tolerating or ignoring it.

“We leave it up to the states to monitor it,” said Elaine Quesinberry, a department spokeswoman.

Norwood sits 7,000 feet high on a mesa in the Colorado Rockies, a six-hour drive southwest of Denver. Its single main street, with laundromat and diner, presents a working-class contrast to the lavish Telluride ski and summer resort 33 miles away. The area was once home to Spanish explorers and mountain men. Robert LeRoy Parker, better known as Butch Cassidy, worked the ranches here more than 100 years ago.

Norwood is so small that its 300 students in preschool through 12th grade attend classes in a single building. The football team fields eight players instead of the usual 11. Still, glass cases lining the school’s hallways show off sports trophies celebrating decades of triumphs from basketball to cheerleading.

“Pain is temporary” reads a poster on the wall. “Pride is forever.”

Inside the school office is a large framed display of Norwood’s victory in the 2011 state wrestling championship.

A year later, in February 2012, members and coaches of the wrestling team boarded a bus to Denver for the state tournament, the culmination of the season. The school principal and local Norwood school officials drove separately to cheer on the team.

The principal’s wife, a banker, grew up in Norwood and they met when he moved to town as a high school senior. They dated in college and returned to Norwood about 12 years ago when an opportunity arose to buy an auto repair shop. He worked for the school for 10 years, first teaching computer science and auto repair, and served as principal for two years.

“We always thought it was a great area to raise kids,” the principal said in an interview. “They were really happy kids, liked going to school, straight-A students.”

Their 13-year-old son was especially good at sports. A sturdy teenager with dimples and a quick smile, he started Pee Wee wrestling at age 3. At home he dazzled his family with his knowledge of sports trivia and enjoyed hanging out with his older brother. Yet in the months leading up to the attack, his mother become concerned that her usually easy-going son was being teased at school, she said.

In February 2012, the boy rode the bus to Denver as the team manager, in charge of videotaping the older high school students at the meet. After the coaches and wrestlers left the bus to weigh in, three older and bigger boys pinned the younger boy down, bound him with the tape, pulled down his pants and assaulted him, according to the principal. His parents were at a hotel, awaiting the start of the meet.

Bloomberg isn’t naming the boys involved because they are juveniles.

Just before the meet started, the principal’s older son heard the attackers laughing about the assault on his brother and told his father.

“I was shocked beyond belief, and I was mad,” the father said. “I do believe I was madder than I have ever been. You’re trying to protect your kids, and then something like this happens.”

The father sought out his son, who told him what had happened. He then confronted Harris, the head coach, who at first said nothing had occurred, according to the father. In subsequent conversations, Harris said: “This happens 1,000 times a day around the U.S.,” the principal recalled.

Harris, who was also school board president, was a builder in Norwood. The two families were close. They had vacationed together, though in recent years they began spending less time together because the principal’s family felt the coach’s boys had become too rowdy, the victim’s mother said.

Harris, through attorney M. Colin Bresee, declined to comment.

The principal said he notified Norwood’s superintendent and the school board’s vice president, both of whom were visiting Denver. Given his personal involvement in the case, the principal agreed to step aside from any discussion of discipline. He said he didn’t go to the police that night because he believed school officials would handle the incident properly.

Back in Norwood, Superintendent David Crews imposed a one- day, in-school suspension on the three boys accused of the assault. Punishment could have ranged from detention to expulsion, Crews said.

Neither Crews nor the school board reported the incident to police; the principal didn’t do so until a month after it happened. Under Colorado law, any school official or employee who has reason to suspect a child has been abused should immediately report the matter to police or social services.

The principal complained to the school board about the punishment meted out to the perpetrators without success, he said. Harris recused himself from the board’s discussions of the incident and later resigned, according to Crews and school board minutes.

“I knew it wasn’t going to be pretty,” the principal said. “When you take on, first, a powerful family in the town — and he is also the school board president, and his kid had done something wrong — there is going to be something coming back at you.”

While the 7th-grade victim didn’t require medical attention after the attack, he soon found himself repeatedly teased by students.

“They would say, ‘What’s been stuck up your butt today?”‘ said his mother. “Things were posted on Facebook, like ‘Rot in hell, liar!”‘

As word spread about the incident, townspeople turned against the principal and his family.

“When I was in school there might have been bullying, but there was none of this crap about telling the school,” said Jennifer Long, a waitress at the Hitchin’ Post Cowboy Bar, a popular eatery on the town’s main street. “How you going to be tough if you don’t get bullied sometimes?” she said.

Long’s husband James Eilmann agreed.

“I got bullied as a kid because I had long hair and earrings,” said Eilmann, a 45-year-old carpenter. “I played football, baseball and soccer and the older kids bullied me. But we always shook hands and it would be over with. But today, you can get prosecuted. It has all gone too far.”

Frustrated by the response of town and school officials, the principal finally reported the incident to the Denver police. The police sent investigators to Norwood and on April 23 they arrested the three boys, charging them as juveniles with kidnapping, sexual assault and false imprisonment, according to the district attorney’s office.

On news of the arrests, anger exploded in Norwood, and it was aimed squarely at the principal and his 13-year-old son. The school board held a series of private meetings with parents who clamored for the principal’s dismissal.

“It should have been left alone,” said Sheldon Cline, a 54-year-old electrician. “It should have been handled through the system here. If you publicize it, it gets blown out of proportion.”

Marie Fouche, a substitute teacher at the school at the time, went to the school board to speak in support of the principal.

“It seemed the whole town was against the victim and his father,” Fouche said. “It was all about punishment and not helping.”

After the arrests, Jessica Bicknase, identified in a police report as the mother of one of the accused, paid to print T-shirts that bore a slogan using the initials of the suspects. Bicknase declined to comment.

A dozen students wore the T-shirts to school one Friday, and someone posted a sign with the same wording on the locker of the victim’s brother, according to the police report, which was reviewed by Bloomberg. Students who wore the t-shirts told police they wanted to support their friends. The victim told investigators he didn’t understand why his friends would support people who attacked him.

When police visited parents of students involved in the T-shirt incident to warn them against intimidating the 13-year- old, who would be testifying against his schoolmates in a criminal case, they found the parents instead focused on attacking the principal.

“The majority of the time was spent with the parents expressing anger at [the principal] for reporting the incident, and for not resigning his position,” according to a police report. “We repeatedly steered the conversation back to the t- shirt incident, but the parents did not want to stop talking about [the principal] and his resignation.”

Denver investigators said they were surprised by the response in the town.

“They blamed our victim,” said Lynn Kimbrough, a spokeswoman for the Denver district attorney’s office, which brought the charges against the three students. “There was a huge backlash, and everybody turned against this boy and his family for bringing trouble to their town.”

After the T-shirt incident, the principal decided to stop sending his son to school, and instead brought his assignments home.

“My son was the outcast,” the principal said. “He was made to feel like he was the one who caused the whole thing.”

Later that year, one of the accused students pleaded guilty to sexual contact without consent; the other two pleaded guilty to third-degree assault. They received varied sentences that included probation, community service and restitution of about $2,500 apiece.

The principal’s contract was up for renewal. After extensive negotiations involving lawyers from both sides, the board renewed his contract and put him on paid leave while it reached a settlement.

The principal was offered another job in a town 200 miles away that pays half his previous salary. The family moved and he enrolled his children in a new school.

Harris was reappointed Norwood’s wrestling coach. He was given a letter of reprimand for leaving students unsupervised on the bus, Crews told police.

In the wake of the incident, Norwood brought in experts from Denver to address bullying and hazing in school, Crews said.

“Something negative like this can make something positive,” Crews said. “We can share ideas on how to treat each other with respect and to know where the boundaries are.”

The principal’s son, now 14, is doing better after having difficulty coping with the incident for about a year, his parents said.

“It seems like we finally have him back,” said his father. “He’s come out of everything he’s been going through since this happened.”

He joined the wrestling team in his new school and just finished an undefeated season. He’s now starting to play football and do weightlifting.

“Maybe it was a wake-up call to get our kids out of that kind of community where people behave that way,” his mother said.