SEATTLE – A Marine was not being hazed or abused when he collapsed and died on a base in Africa, but his superiors broke rules when they had him exercise as punishment for slightly injuring another Marine, a commander concluded.

Lance Cpl. Dustin Canham chose to do push-ups and other exercises to avoid having a black mark on his record and his death March 23 was due solely to a heart condition, said Lt. Gen. Samuel T. Helland, commander of U.S. Marine Corps Forces Central Command, in a summary provided to Canham's father.

The Naval Criminal Investigative Service is investigating Canham's death separately, but the Marine report includes some statements other Marines made to NCIS.

Canham, 21, of Lake Stevens, Wash., and a Marine private had been playing catch with a rock that day at the U.S. base in Djibouti, according to the documents. The private told investigators he looked away just before Canham threw the rock, which hit him in the mouth. It chipped his tooth, but the injury did not require medical attention.

Platoon Sgt. Jesus Diaz, 24, of Bakersfield, Calif., informed a staff sergeant, who noted that putting the incident in Canham's record could hinder his promotion.

The staff sergeant recommended that Diaz give Canham a choice of receiving a mark on his record or performing physical training, and Canham chose the latter.

“(The staff sergeant) and I both felt LCpl Canham was a good Marine, and did not want to have to write him up for this incident,” Diaz told an NCIS investigator in a signed statement.

The names of witnesses were redacted in the file, but The Associated Press independently identified Diaz and the other superior who brought Canham into the tent, Cpl. Richard Abril, 28.

With Diaz watching, Abril and Canham exercised together in a “daily seven” routine of 30 push-ups followed by leg lifts and other core-body work. Only three minutes after they started, Canham “stopped, went to his knees, sat back on his hips, leaned up against a rack and passed out,” Abril wrote in a statement to investigators.

Diaz ran for help as Abril performed CPR until emergency responders arrived, they wrote. But he could not be revived. An autopsy found a mildly enlarged heart with a thickening of the left ventricular wall, which left Canham vulnerable to cardiac arrest.

The investigative file makes clear that the use of physical training was not authorized. “Extra military instruction” – the assignment of extra tasks – may be given to correct a Marine's shortcomings, but not as punishment, Helland wrote.

However, he wrote, the training was neither harsh nor abusive and was not the cause of death.

In letters shortly after Canham died, the Marines told his family he collapsed while exercising, but the letters didn't explain why he was inside the tent with two superiors. Canham's father, Mark, and widow, Devyn, suspected he might have been hazed or forced to work out until he died.

Mark Canham said he wants to see for himself if Diaz told the truth to investigators.

“If he could tell me to my face what happened in that tent, then I'd believe it,” he said.