The Marine Corps punished at least eight drill instructors and some officers in response to allegations of hazing and other abuses last year at the service’s recruit training center at Parris Island, S.C., according to Marine officials and documents obtained by The Washington Post.

Investigators found numerous incidents in which recruits had been abused by the Marines training them, despite efforts by Marine Corps leaders to stamp out the problem following the death of a 20-year-old trainee, Pvt. Raheel Siddiqui, in 2016.

A Marine spokesman, Capt. Bryan McDonnell, said in a statement that the drill instructors “received appropriate administrative actions of varying degrees relative to substantiated allegations,” indicating commanders determined criminal charges were not necessary.

Several officers overseeing the drill instructors also received some form of administrative punishment, McDonnell said, without providing specifics.

The cases, which have not previously been disclosed to the public, occurred in the 4th Recruit Training Battalion, a unit in which female drill instructors train female recruits. The investigations were opened as the service began considering more fully integrating male and female recruits during training, as in the other services.

Documents detailing the investigations were released to The Post through the Freedom of Information Act.

Investigators examined numerous allegations against drill instructors in the battalion’s Papa Company, including one case in which a recruit’s tooth was chipped in July 2018.

In a handwritten statement, the recruit recalled that she tried to tell other recruits to slow down while they were moving in formation, upsetting the senior drill instructor. The recruit could not recall whether the Marine pushed her arm or the weapon itself.

“I knew I was in the wrong for overstepping when I shouldn’t have, but I wasn’t used to anyone messing with the weapon," the recruit wrote.

The senior drill instructor later found the recruit on a bathroom bench at night writing to a former Reserve Officer Training Corps instructor, a sergeant major, about the incident. The recruit told an investigating officer the instructor confiscated several letters and asked other recruits the next day whether they would say she had abused them.

The drill instructor said she eventually told others in control about the incident, and the recruit was transferred to a different platoon. The drill instructor was informed she could be charged with failure to obey an order or regulation, according to military documents, which do not clarify what commanders chose to do.

In August, another 4th Recruit Battalion drill instructor slammed a recruit’s hand with a foot locker, according to the documents. The recruit received medical treatment and later reported she believed the incident was an accident. However, other recruits said drill instructors told them to say it was unintentional, according to the investigation. It is not clear whether commanders determined what happened.

One recruit interviewed in the case reported she and three other Marines were forced to go through a chamber that introduces recruits to CS gas twice within minutes during training, instead of once as typically required. The recruit wrote in a witness statement that drill instructors said “enlisted look out for enlisted,” something she construed to be a message to keep quiet.

In a separate investigation, 13 people reported a senior drill instructor in the battalion for acting inappropriately, the documents said. A case was opened after a recruit told an officer in May 2018 that she was ordered to put “feces soiled underwear” on her head, and a second recruit backed up the allegation, documents said.

In a statement to an investigating officer, the senior drill instructor involved said the incident occurred after a recruit left underwear under her bed. She asked the recruit if she understood that doing so was a problem and then suggested she would understand better if she put them on her head, the drill instructor recalled, according to the documents.

“I was speaking hypothetically and failed to handle the situation with a clear mind through frustration,” the drill instructor wrote. “I was not trying to embarrass the recruit and more so wanted her to understand why and how it wasn’t acceptable. The underwear didn’t have feces.”

The documents do not make clear what the investigation found, or whether the drill instructor was disciplined.

Another investigation was launched in February 2018 after several recruits reported anonymously that they had been roughed up, and one said a drill instructor had threatened to break her neck.

The senior officer in charge of Parris Island, Brig. Gen. James Glynn, said in an email to The Post that the investigations help the service determine what is necessary to maintain “effectiveness and discipline” during recruit training. He defended the behavior of the majority of the Marines under his command.

“There’s a more intriguing story in the more than 600 Marines who are drill instructors here, and their families, and their personal and professional investment in transforming young women and men into Marines,” Glynn wrote. “The 100+ hrs a week they dedicate to their role, and the support of their families, is the source of transformative energy that makes this remarkable process possible. The fact that 98% of them do so without any allegation is the storyline I commend to you."

The Post has obtained documents outlining more than 20 other substantiated hazing and abuse cases at Parris Island and the service’s West Coast recruit training center in San Diego that span the past seven years.

In the most serious, former Gunnery Sgt. Joseph Felix was convicted of maltreatment and sentenced to 10 years of imprisonment for subjecting Muslim recruits, including Siddiqui, to verbal and physical abuse. Siddiqui fell to his death over a railing after running away from Felix, who had slapped him in the face. Authorities determined the case to be a suicide, but Siddiqui’s family has disputed that finding.