At Parris Island in South Carolina, the Marine Corps’ oldest and most famous training center, the 3rd Recruit Training Battalion was called “the Thumping Third” — a nickname it earned through drill instructors’ reputation for dishing out physical abuse.

“They see it as a badge of honor, like they were the only real Marines,” said Kate Germano, a retired lieutenant colonel who oversaw training of women at Parris Island.

But in that atmosphere, a recent report from the Marine Corps found, a drill instructor under investigation for calling a Muslim recruit a “terrorist” and ordering him into a running clothes dryer where he was burned on his arm and neck, was kept in his job. The instructor later slapped, abused and harassed another Muslim recruit who jumped to his death from the barracks.

Now a widening Marine Corps inquiry into the death and other hazing at Parris Island — and of the chain of command that allowed it to happen — has identified 20 enlisted Marines and officers, including many in the 3rd Battalion, for potential criminal charges. The lieutenant colonel in charge of that battalion, the colonel in charge of all training at Parris Island, and his sergeant major have been relieved of their command.

And with possible prosecutions looming, the Marine Corps is grappling with how to continue to foster the Jarhead culture that prizes toughness while also safeguarding recruits and rooting out bigotry.

Leaders have called the problems in the 3rd Battalion an anomaly, noting that regulations forbid instructors from laying hands on recruits or even calling them anything but their name. But many in the ranks have defended harsh treatment during training as a rite of passage that recruits must pass before taking on a job that can be grueling and terrifying. Anyone who can’t hack it, they say, should find other work.

“It’s called becoming a Marine! We all went through it. Marine Corps basic training is hell on earth as it should be,” one Marine veteran, echoing the sentiments of many, said in a comment beneath a Marine Corps Times article on the hazing.

Even after basic training, a long, hallowed culture of physical and verbal battering awaits Marines who join infantry units. New arrivals, called “boots,” are often harassed and harangued by their seniors to toughen them for combat.

Still, in light of the abuses at Parris Island, that hardening process is receiving more internal scrutiny.

“When America’s men and women commit to becoming Marines, we make a promise to them,” the Marine Corps commandant, Gen. Robert B. Neller, said in a statement after the investigations were released. “We pledge to train them with firmness, fairness, dignity and compassion. Simply stated, the manner in which we make Marines is as important as the finished product.”

According to the Marine Corps report, which was reviewed by The New York Times, in summer 2015, a drill instructor, whose name has not been released, made a Muslim recruit do push-ups in a shower, telling him it was his job to root out spies. The instructor then said that the 6-foot recruit needed to “dry off” and ordered him into a clothes dryer.

After running the dryer for 30 seconds, the instructor asked whom the recruit was working for, the report found. When the recruit replied “nobody,” the instructor ran the dryer again, then asked the recruit his religion. The recruit, who had started crying, replied “Islam.” The instructor ran the drier for a longer time, then asked the recruit if he was still a Muslim. When the recruit said “yes,” the instructor ran the dryer again.

In November, after completing basic training, the recruit reported the abuse and the Marine Corps started the investigation. But commanders at Parris Island allowed the instructor to continue training recruits.

In March a 20-year-old Muslim, an American of Pakistani heritage named Raheel Siddiqui, was placed in the instructor’s platoon. Siddiqui, who was valedictorian of his high school class in Michigan, struggled to adjust, and a week after arriving said he was suicidal. He eventually said he was no longer suicidal, and was allowed to continue training. According to the report, the instructor thought Siddiqui was feigning illness to get out of training.

On March 18, Siddiqui gave a note to the instructor before breakfast, asking to go to sick call because he “coughed blood a few times last night” and “completely lost his voice and can barely whisper.” The instructor yelled at Siddiqui and made him do sprints the length of the barracks, which are known in the Marine Corps as squad bays.

Siddiqui, crying, collapsed, holding his throat, at which point the instructor slapped him in the face, loud enough that it could be heard throughout the squad bay.

According to the report, after being hit, Siddiqui got up, ran out of the barracks and jumped into a stairwell, falling 38 feet. He was pronounced dead a few hours later.

Investigators ruled his death a suicide but noted a pattern of abuse and hazing in training as well as an “absence of oversight and supervision at various levels of command,” a Marine Corps official said.

The instructor and other drill instructors involved were immediately removed from their positions. Lt. Col. Joshua Kissoon, who was in charge of the 3rd Battalion, was removed a few days later for his actions in the clothes dryer investigation, a Marine spokesman said.

And the battalion commander’s boss, Col. Paul D. Cucinotta, who was in charge of all training at Parris Island, and his senior enlisted adviser, Sgt. Maj. Nicholas Deabreu, were removed in June.

The report has identified 20 people for punishment, which could include formal admonishment, nonjudicial punishment or criminal charges.

The Marines note that the Corps trains nearly 40,000 recruits a year and has fewer than 50 substantiated cases of hazing annually. Drill instructors are given days of training on regulations and taught how to discipline troops without physical or verbal abuse. All instructors are told the story of Ribbon Creek, where a drunken staff sergeant took his platoon on a punitive night march through the swamps near Parris Island in 1956, and six recruits drowned.

The Marine Corps has announced a number of fixes, including putting more junior officers in with platoons to observe training. It has also made suspension mandatory for any Marine being investigated for recruit abuse.

Many of the reforms announced by the Marines are already on the books and not being enforced, said Germano, who was relieved of her command at Parris Island in 2015, after a controversy that involved her push for more resources and better training for female recruits. She is now the chief operating officer of the Service Women’s Action Network, an advocacy organization.

“You can make all these rules, but Parris Island still has a permissive culture,” she said. “It’s like they have this tradition and they are afraid they will ruin it if officers get too involved.”

The reputation of “the Thumping Third” was well-known when she commanded a sister battalion, she said, but leaders, rather than curtail it, rewarded the 3rd Battalion with the newest barracks.

“The culture was allowed to flourish,” Germano said. “There is a hands-off approach. There is a belief that officers don’t make Marines, Marines make Marines, and so a lot of times, the leaders are not in the squad bays at night, or in all the places they need to be.”