Concerns about an alleged sex offender who families believe abused boys at a Sussex school were ignored by the authorities, parents have claimed.
Darren Turk, ex-head of care at Frewen College, killed himself a day before he was convicted. The verdicts were later overturned but appeal judges found nothing to suggest they were unsafe.
Families have told of the boys' trauma and said it could have been stopped.
The school said its culture and leadership were now entirely different.
Mr Turk's family have always protested his innocence, but several parents and a former pupil of the school for children with learning difficulties have claimed the boys were abused and left dealing with issues including addiction, depression and homelessness.
All the names of those who have spoken to the BBC have been changed.
Judith, said her son Sam, then 12, phoned her crying one morning and said someone had done something "rude", but she believes Mr Turk then came into the room.
"He raped him that morning. I'm positive about that," she said.
Judith said she wrote to a school governor, but said he replied with a letter threatening legal action.
Former pupil Robert said Mr Turk assaulted him and trod on his face.
He believes he and other pupils were the first to report Mr Turk in 1996, but he said the school claimed the boys were lying.
- 1996 - Darren Turk starts work at Frewen College as a member of the care staff. Pupils say first complaints are made that year.
- 1997 - Mr Turk is promoted to head of care.
- 1999 - Concerns prompt an investigation by police and social services.
- 2002 - A boy reports a rape. Mr Turk is dismissed and questioned.
- 2002 and 2003 - Sussex Police refer sex assault cases to the Crown Prosecution Service but say there is no realistic prospect of conviction.
- 2016 - Mr Turk is charged. He kills himself the day before a jury convicts him on 10 out of 16 counts.
- 2017 - Appeal judges rule the verdicts after Mr Turk's death were irregular and order them to be set aside, with the convictions annulled.
Jackie said she complained about Mr Turk - who she claimed introduced her son to cannabis before he turned to alcohol and heroin - but her concerns were not addressed.
She said she kept the letters she sent to the-then head teacher Simon Horsley, who now runs a tutoring business in Wakefield.
Mr Horsley told the BBC there had not been a cover-up, he acted in good faith throughout, and could not remember there being many complaints.
When asked by the BBC if he took any responsibility for what had happened, he said: "I was the headmaster."
The school's current principal Nick Goodman said: "The leadership, staff and culture of Frewen College are now entirely different.
"We have rigorous safeguarding measures in place including meticulous recruitment processes."
Mr Turk was convicted after his death of offences between 1996 and 2002 against boys aged 11 to 15.
He started work at the school as a member of care staff in 1996 and became head of care a year later.
In 1999, concerns prompted an investigation into Mr Turk by police and social services.
Their draft report listed nearly 20 allegations, but the team concluded managers had monitored the situation and most claims were reported too late.
In 2002 a boy reported being raped. Mr Turk was dismissed and questioned but not charged until 2016.
Sussex Police said they referred sex assault cases to the Crown Prosecution Service in 2002 and 2003 but there was no realistic prospect of a conviction.
Last year, Lewes Crown Court jurors convicted Mr Turk on 10 out of 16 counts, but appeal judges said the trial judge "was not entitled to continue" after Mr Turk died and the verdicts must be set aside.
East Sussex County Council has not commented.