Greater Manchester Police acted after reports people were ordered to shred documents about abuse claims at Knowl View school between 1969 and 1995.
The school cared for boys from dysfunctional backgrounds and was open for more than 20 years.
More than 25 ex-pupils allege they were sexually and physically abused.
BBC Radio Manchester has been told the CPS is now reviewing whether prosecutions can be brought.
A spokeswoman for the CPS said: "We have received a file from Greater Manchester Police in relation to their investigations into allegations relating to Knowl View School. This is currently under review."
Twenty-eight people including former members of staff and pupils have been interviewed under caution as part of the inquiry, which was launched by Greater Manchester Police in 2012.
The suspects were aged between between 35 and 80.
Police have also examined allegations made against the late Rochdale MP Cyril Smith, who allegedly abused 20 teenage boys between 1960 and 1987 at Knowl View, Cambridge House hostel, and others parts of the town.
Despite being subject to allegations and investigations during his career, the Liberal politician was never prosecuted before his death in 2010.
GMP also appointed an independent panel to oversee their investigation into an alleged cover-up at Knowl View.
It is a moment many of the boys who attended Knowl View thought would never come because they always felt they were disbelieved by those in authority about the abuse they suffered.
Knowl View was open from the very end of the 1960s until the early 1990s.
It was jointly run initially, by Bolton, Rochdale and Oldham borough councils and Lancashire County Council.
And it appears from its earliest days physical and sexual abuse took place within the school walls.
Indeed I've spoken to Tony Blair's chaplain Fr Michael Seed who describes being sexually abused by one of its teachers David Higgins.
Higgins remains the only person to date to have been convicted of offences at Knowl View.
Evidence gathered as part of a major police inquiry into abuse at a school in Rochdale is now being considered by the Crown Prosecution Service.