Social services dealing with Soham killer Ian Huntley failed to act on allegations he had sexual relations with 11 girls before 2001.
Ian Huntley had sexual relations with several young girls
A report details cases of girls dealt with by North East Lincolnshire Social Services when Huntley was living in the Grimsby area in the mid-1990s.
Sir Christopher Kelly, who conducted the review, said opportunities had been missed by social workers and police.
He said the killer's history "should have rung significant warning bells".
Sir Christopher's report looked specifically at how social services dealt with allegations that Ian Huntley had sex with under-age girls during that time.
North East Lincolnshire Area Child Protection Committee asked for the Serious Case Review following Huntley's conviction for murdering the 10-year-olds Jessica Chapman and Holly Wells.
The school caretaker had been mentioned in reports to social workers four times in less than a year for underage sex with different teenage girls while he was living in the Grimsby area.
The report looked in detail at six separate instances when Huntley was said to be having sex or in a relationship with 15-year-old girls.
On another occasion investigated by the report he was having sex with a 13-year-old.
And a girl's claim that she had been sexually assaulted by Huntley was also looked at.
The testimony of one young woman was cited claiming that Huntley's penchant for young girls was "well known in the local community".
In the report Sir Christopher said: "There are not many people who come out of the events we have described with a great deal of credit."
He claimed that there was poor decision-making in a number of cases, and the care given to some of the young people involved was "less than adequate".
He added: "There were significant shortcomings and inconsistencies in the way information was shared between some of the agencies, particularly social services and the police.
June-August 1995: with a 15-year-old girl
Early 1996: living with another 15-year-old
Early 1996: having sex with a separate 15-year-old
Early 1996: relationship with a 17-year-old
Early 1996: having sex with a 13-year-old
September 1997: having sex with another 15-year-old
October 1997 brief sexual relationship with a 15-year-old
July 1998: allegation of indecent assault on another girl
1995-1997: In a relationship with a girl who was 15 years old when it began
"And some of the connections that could have been made to identify a pattern in Huntley's behaviour were missed."
The social services department in Grimsby had no system capable of tracking the various allegations made to it and nothing allowing cross-referencing.
"With some justification they regard that as the role of the police," Sir Christopher said.
But he added: "We have been told that North East Lincolnshire at the time was aware of several individuals who might be a danger to children but Ian Huntley was not among them."
He also considered the idea of a searchable database of alleged offenders for child care authorities.
Recommendations in the Bichard report that a national code of practice should be established dealing with record retention by the police were echoed by Sir Christopher.
"In our view there is a strong case for considering analogous guidance covering the retention of education and social services files relating to children where child protection or children in need issues have arisen," he concluded.
Huntley was handed two life sentences by the Old Bailey in December 2003.