A police investigation into a young offenders' centre has now heard claims from more than 140 people that they were abused between the late 1960s and the mid-1980s.
Detectives announced in August they were starting a new investigation into allegations young men sent to Medomsley Detention Centre near Consett, County Durham, were abused by staff, which led to 83 people coming forward.
That number has now increased to 143 and police chiefs said detectives were left shaken by some of the accounts they heard.
Detective Superintendent Paul Goundry, of Durham Constabulary, said: "We said from the outset this was going to be a long and complex investigation which we fully expect will last at least another 12 months.
"So far we have been contacted by more than 140 former inmates of Medomsley, who have reported they were victims of either sexual or physical abuse at the centre between the late 1960s and the mid-1980s.
"The accounts we have heard have been horrific and have shaken some very experienced detectives who are working on this.
"It is obviously distressing to hear from so many victims, but at the same time I am relieved they have shown the confidence in us to get in touch and allow us to help them.
"Our efforts are directed not just at establishing what happened in Medomsley over that period but ensuring the victims are left in a better place and get the support and advice they need."
In 2003, a previous police investigation called Operation Halter led to the conviction of Neville Husband, a prison officer at the centre.
Husband was initially jailed for eight years after being found guilty of abusing five youngsters.
The publicity surrounding the trial then led to others coming forward and Husband was subsequently jailed for a further two years for these attacks.
After being released from prison he died from natural causes in 2010.