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The death of a young recruit at the Marine Corps' vaunted Parris Island training camp has triggered a broad investigation into hazing and abuse, the corps said Thursday.

The probe, launched following Raheel Siddiqui's March 18 death, has so far led to allegations against 15 drill instructors and other ranking officers at the South Carolina facility. The activity includes "potential violations of Marine Corps orders to include hazing, physical abuse, assault and failure of supervision," the Marine Training and Education Command said in a statement.

Siddiqui, a 20-year-old high-achieving son of Pakistani immigrants from Michigan, died 11 days after arriving at Parris Island, when he fell three stories off a barracks stairwell. The Marines labeled the death an apparent suicide, according to media reports.

Raheel Siddiqui, 20, died during Marine Corps recruit training at Parris Island, South Carolina on March 18. via Facebook

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A few days before his death, Siddiqui approached his senior drill instructor and told him he wanted to quit and kill himself, according to an initial casualty report sent to Siddiqui's family and cited by the Wall Street Journal. After officials visited him, he retracted the threat and was put under observation, according the Journal's description of the report.

He returned to training before apparently leaping to his death on the morning of March 18.

Rep. Debbie Dingell of Michigan heard about the death, and wrote a letter to the commandant of the Marine Corps, Gen. Robert Neller, questioning whether it was related to hazing.

So far, it is not clear whether hazing played a direct role in Siddiqui's death, or if it was related to his ethnicity or Muslim faith.

US Marine Corps recruits march during 6-mile hike at the beginning of the 54-hour Crucible exercise January 6, 2011 at the Marine Corps Recruit Depot on Parris Island, South Carolina. Robert Nikelsberg / Getty Images

But the continuing probe found other instances of potential misconduct dating back to at least November 2015, according to the Marine Training and Education Command. The conduct appeared to be isolated to a single unit: the 3rd Recruit Training Battalion.

Among the problems turned up by the probe is a drill instructor, whom the Marines did not identify, who was placed in charge of recruits despite having already been subject to a prior investigation. The Marines did not detail what that earlier probe concerned, but the Journal reported it involved accusations that he hazed minority recruits.

Most Marines under investigation have been assigned to duties that do not involve direct access to recruits, the Training and Education Command said.

Others have lost their jobs.

The Marines removed its second-in-command at Parris Island, Col. Paul Cucinotta, according to the Washington Post. It did the same to Lt. Col. Joshua Kissoon, who oversaw the 3rd Recruit Training Battalion, and Sgt. Maj. Nicholas Deabreu, one of Cucinotta's senior advisers, according to the Post.

"We take every allegation of misconduct very seriously and will review each investigation carefully," said Maj. Gen. James W. Lukeman, head of the Marine Training and Education Command. He added: "The safety of the recruits and the integrity of the Marine Corps recruit training program are among our top priorities and, once the investigations are complete, we will take necessary administrative and judicial action as warranted to ensure proper accountability."