Investigators are slowly unraveling the mystery of a mass grave found at a Florida boarding school for boys that had a sordid reputation for torture, rape and murder dating back nearly 100 years. 

In a report released last week, University of South Florida researchers outlined what they have so far learned as anthropologists sift through the remains of 51 exhumed people found buried at the Arthur G. Dozier School in Marianna, the Associated Press reported. 

So far, six of the bodies have been identified, including a boy who ran away from the school only to be found dead with a shotgun placed across his legs. 

Interviews with former students and staff at the reform school, which closed down in 2011, revealed the existence of a "rape dungeon" where boys as young as 12 were sexually assaulted. Others were subjected to beatings and even killed, their deaths going unreported by the school or listed as missing cases, the AP reported. 

"Maybe I've been doing this too long, but I'm not surprised at what horrible things people do to one another," USF anthropologist and mass grave-researcher Erin Kimmerle, also the team leader, told the AP. "It's just really sad the way people treat one another, which may be in part what's captured the public's attention on this - just the sense that it's not right."

Four of the six victim's identities were confirmed through DNA provided by their families.

One victim was 6-year-old George Grissam. The school sent him to be a house boy at another residence in 1918. He died after he was sent back to the school unconscious, although it is still unknown exactly what happened.

His 8-year-old brother Ernest Grissam also vanished from the school, but records simply listed him as "not here," according to the AP. 

Another victim was Robert Hewitt, who ran away from Dozier and was hunted down by men the school sent. He was found dead a few miles away at his family's home with a sheet over him and his dad's shotgun placed over his legs. 

With not even half of the mystery of Dozier solved - there were over 100 unmarked graves at the school - former students whose memories of abuse are still raw anxiously wait for a resolution.

"A lot of us are seeking closure," John Bonner, who attended Dozier from 1967 to 1969, told the Tampa Tribune. "A lot of people were abused there. A lot of people's rights were trampled on. I was strapped with the belt so many times, one time just for looking at a supervisor the wrong way."