Detectives investigating sexual abuse at a detention centre have admitted they were shocked by the scale of the allegations after more than 500 potential victims were identified.
It was now thought an organised paedophile ring was operating in the 1970s and 1980s at Medomsley Detention Centre near Consett, County Durham.
Police announced in August they were starting a fresh investigation into abuse at the centre for young offenders who were mostly convicted of minor crimes.
In 2003 a previous police investigation led to the conviction of Neville Husband, a prison officer at the centre.
Husband was initially sent to jail 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.
Now Detective Superintendent Paul Goundry, leading a 70-strong team, has told the Guardian: "We always knew this would be a major inquiry but the scale of it, and the sheer number of victims who have come forward, has been a shock."
Husband, who went on to become a church minister, was in charge of the kitchens at Medomsley and would single out youths for sexual abuse, particularly those who had been in care and did not have strong family ties.
His former colleague Leslie Johnson, a storeman, was jailed for six years in 2005 for sexual offences. He has also since died.
Police originally believed the pair were operating alone, but that view has changed after speaking to many victims.
Mr Goundry told the Guardian: "From the statements, there is growing evidence to suggest there was an organised paedophile ring operating in Medomsley."
He said the experience of many of the victims, sent for detention for relatively petty crimes, had ruined the rest of their lives.
The inquiry team was also investigating physical abuse of young detainees.