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Researchers excavating unmarked graves at a notorious reform school in the Florida Panhandle said Tuesday that they have retrieved the remains of 55 bodies, nearly double the number originally believed to be buried there over many decades.

The exhumations mark a milestone in a painstaking effort to unravel the longtime mystery of what happened to scores of children who were sent to the former Arthur G. Dozier School for Boys in Marianna, Fla., and died. The institution for wayward youth, which the state opened in 1900 and closed in 2011, faced allegations throughout its history of brutal beatings, rapes and forced labor. Relatives of boys who died there, as well as former students who survived, have long believed some kids perished in suspicious circumstances.

Despite a string of state and federal investigations over the years, school officials repeatedly denied wrongdoing. Florida Attorney General Pam Bondi, who supported the excavation effort, said, "Hopefully, surviving family members are closer to the closure they deserve. It's such a tragedy that so many young boys lost their lives there."

Because the school kept shoddy and sometimes contradictory records, burial locations weren't always recorded, and the cause of death was sometimes listed as "unknown." A Florida Department of Law Enforcement inquiry completed in 2009 had concluded that 31 boys were buried in a cemetery on the 1,400-acre campus.

In announcing their findings Tuesday, a team of forensic anthropologists at the University of South Florida here painted a grim picture. Among the thousands of artifacts they retrieved were bones and teeth. There was also a metal plate from a coffin, reading "At Rest," and a marble in a boy's pocket. They are now analyzing the remains to try to determine how the boys died and submitting DNA samples for testing in hope of identifying the boys and returning them to relatives for proper burials.

"We're hoping to bring the families resolution and hopefully some sense of peace," said Erin Kimmerle, a USF professor leading the research team.

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