US investigators in Florida using ground-penetrating radar and soil samples say they have found at least 50 graves - 19 more than officially reported - on the grounds of a former state reform school for boys.
The Dozier School has been the target of numerous allegations of abuse and mysterious deaths of children during the more than 100 years of its existence.
In a report to the state, anthropologists and archaeologists at the University of South Florida (USF) in Tampa said their research has identified evidence of more grave shafts in and around a cemetery at the now-shuttered school in the Panhandle city of Marianna.
The research team plans to return to the site in January to continue the research, possibly leading to exhumation of human remains.
Relatives of a boy who died and was buried at the school under mysterious circumstances in the 1930s attended a press conference to present the report's findings. They are seeking to reclaim his remains.
Also in attendance were several men who were sent to the school as teenagers and said they endured repeated severe lashings with a leather strap until they bled in a building dubbed the "White House."
"First and foremost to us are the rights of the families and people's rights to have justice and accountability for their families," said assistant anthropology professor Erin Kimmerle, one of the lead investigators.
A 2008-2009 study by the Florida Department of Law Enforcement that relied on the school's own records reported that 81 people had died at the school and 31 were buried on school property, their graves today marked by white metal crosses.
USF researchers and students found records of 98 deaths of boys between ages 6 and 18 plus two adult staff members at the school between 1914 and 1973.
The research that began in early 2011 and included an examination of state death records, revealed missing, conflicting and "sloppy" record-keeping about the people buried at Dozier and how they died.
The institution, the largest reform school in the state, opened in 1900 and closed in 2011.
The most common causes of death were disease, fire, physical trauma and drowning.
But seven died during escape attempts - including one 16-year-old who suffered gunshot wounds to the chest - and 20 died within the first three months of arrival, the report said.
"We as a family are eternally grateful," Glen Varnadoe said after the press conference.
His uncle, Thomas Varnadoe, died at the school in 1934 one month after he was remanded there at age 13 along with Glen Varnadoe's father.
Both were accused of "malicious trespassing" through a woman's yard on the way home from school.
"We really have no idea where Thomas is buried, on the north side or the south side of the campus," said Varnadoe, adding that his father was too traumatized to speak about his time at the school except at the very end of his life.
That decision to close Dozier followed investigations of abuse that had dogged the school since the year after it opened.
Wansley Walters, secretary of the Florida Department of Juvenile Justice, said in the statement that the department "will continue to work with the researchers at the University of South Florida on how best to provide them access to the site."
The state's attempt to sell the property at auction was halted this year by a judge after the Varnadoe family filed a lawsuit regarding Thomas' remains.