The report of the Bichard Inquiry into how double murderer Ian Huntley was employed as a school caretaker in Soham was published on Tuesday.
Sir Michael Bichard has spent months analysing the evidence
Following his conviction for the murders of Holly Wells and Jessica Chapman, it was revealed Huntley had been accused of a string of sex crimes.
The inquiry heard from 57 witnesses and gathered 2,000 pages of evidence.
BBC News Online looks at the key errors of police, social services and the education system exposed during the probe.
Nine allegations of rape, indecent assault on an 11-year-old girl and sex with underage girls while Huntley was living in Grimsby were not shared between Humberside and Cambridge forces.
No record of Huntley's past had been retained by Humberside Police, even though he was charged in one of the rape cases before it was later dropped.
Huntley had confessed to having sex with one underage girl in 1995 but was not charged or cautioned because she did not want to prosecute.
He could have been cautioned though. And if he had, his name would have been on the national database for at least five years.
Ian Huntley didn't have to try hard to evade detection, police admitted
Huntley's name was, however, logged on Humberside Police's own local computer system. In 1999 PC Michael Harding wrote a file on him, saying he was clearly a "serial sex attacker".
But the report was deleted during a review of the database a few months before Huntley applied for the job at Soham Village College.
Chief Constable David Westwood conceded their intelligence system had "failed almost completely" and admitted he had been wrong to blame the Data Protection Act for the vetting process.
The force also failed to update Police National Computer (PNC) records to include Huntley's alias surname of Nixon, so the response to any checks would have been "no trace".
They had twice been told Huntley and Nixon were the same person.
Staff responsible for vetting job applicants such as Huntley were not able to access a database with information about sex offences and children.
Even if Humberside's record keeping had not been flawed, it may have proved academic after it emerged Cambridgeshire Police did not ask it for a vetting
Cambridge admitted it was "more likely than not" that it had never asked Humberside for information on Huntley. Before the inquiry it maintained a fax request had been sent.
Chief Constable of Cambridgeshire Police Tom Lloyd said his officers had not vetted Ian Huntley properly and its systems contained "weaknesses".
Tom Lloyd admitted his force had made "disturbing" errors
Two specific human errors were also made during the vetting process.
One staff member entered Huntley's date of birth incorrectly into the Child Access database, while another only looked on the national database under Huntley's alias surname Nixon.
Checking under Huntley would at least have thrown up a burglary charge from 1995 - that factor alone would have prevented him getting the caretaker's job, said the school's head teacher Howard Gilbert.
An internal investigation found "shortcomings" in the supervision and management of Cambridgeshire Criminal Records Bureau.
The report's author found an "apparent complacency" towards child access checks.
An officer told the inquiry the unit responsible for child access vetting was overworked. When Huntley applied for the Soham job in December 2001 he was one of 1,723 people being checked.
The education authorities
Head teacher of Soham Village College Howard Gilbert said he did not follow up any of the five references Huntley provided at his interview, two of which were undated and three of which were almost 18 months old.
The head of Soham Village College did not check Huntley's references
The director of a firm doing background checks for the Local Education Authority said she ticked the police check forms to say she had verified Huntley's personal details, when she had not done so.
Maureen Cooper of Education Personnel Management Ltd said she was not equipped to check Huntley's date of birth alias names or previous addresses.
North East Lincolnshire Social Services
A senior social worker failed to link three underage sex allegations made against Huntley within one month in 1996.
Phil Watters investigated each case, and also failed to connect them with an earlier incident in which Huntley admitted sleeping with a 15-year-old girl.
Mr Watters also admitted a letter from a local deputy head teacher raising concerns about Huntley had not been passed on to police.
Deputy director of the council's child care department Martin Eaden said he thought the social services' handling of one specific allegation of underage sex was "totally inadequate in every sense".
The case was closed without the girl having been seen, her whereabouts established or her welfare assured.