Five men are due to be sentenced for sexually exploiting the "profound vulnerability" of a 15-year-old girl in Rochdale.
Following their convictions, police apologised to the victim for failings in their initial probe into the defendants.
Many of her abusers plied her with vodka and cannabis before committing their offences, which took place in 2008 and 2009, Manchester Minshull Street Crown Court heard.
The majority of the defendants were only arrested last year after the grim portrayal of a largely Pakistani heritage child sex ring preying on white girls in the town emerged into the public domain in a separate trial at Liverpool Crown Court which attracted huge publicity.
But one of the offenders, Congolese refugee Freddie Kendakumana, was first arrested and interviewed by Greater Manchester Police (GMP) in December 2008 after the girl - also white - complained to police that he had raped her the month before.
The girl was told at the time by an interviewing male officer that it was important not to have any future dealings with Kendakumana while the investigation continued but she later confessed that she had bumped into him at a flat. Soon afterwards, she went on to have consensual sex with his friend when still aged 15, although that man knew she was under-age.
The investigation against Kendakumana, 27, was dropped before he was rearrested years later and finally charged, along with his co-defendants, in October 2012 - nearly four years after the girl made the initial complaint as several men went on to abuse her in the intervening period.
By that time the girl had undergone numerous video-recorded police interviews from the end of 2008 to October 2011, totalling more than 23 hours.
Following the convictions, Assistant Chief Constable Dawn Copley, of Greater Manchester Police, said: "We must acknowledge that there were some failings with the initial investigation carried out by Rochdale division into a complaint of rape by the victim in 2008.
"The suspect was arrested on suspicion of rape, but he was released without charge. The case was investigated and the officer who supervised the investigation took the decision to discontinue the case.
"In 2009 the victim in this case made a number of disclosures to the police about some of the defendants in this case.
"A decision was made to file the information gathered during this interview as intelligence and the decision was supported by the officer's line manager."
A review of the probe by GMP's sexual crime unit highlighted a number of failings, Ms Copley added.
The matter was referred to its Professional Standards Branch in March 2011 and "formal management action" was given to two officers.
The investigation has also been referred to the Independent Police Complaints Commission.
The victim was first prompted to go to the police in 2008 on the advice of a health support worker when she disclosed that Kendakumana was sexually forcing himself on her.
But social care and health professionals dealing with the youngster failed to pass on her other confessions in 2008 and 2009 that she was having consensual sexual contact with a string of older men whom she labelled "boyfriends".
The victim, now aged 20, gave evidence against the five defendants in two trials earlier this year.
Kendakumana, of Illminster, Rochdale, was convicted of rape and sexual activity with a child. He was cleared of a second count of rape.
Two other men, Mohammed Rafiq Abubaker, 25, of Freehold, Rochdale, and takeaway worker Roheez Khan, 27, of Ashfield Road, Rochdale, were found guilty of sexual activity with a child. Khan was also convicted of witness intimidation.
A fourth man, Chola Chansa, 33, of Illminster, Rochdale, pleaded guilty to sexual activity with a child.
Taxi driver Abdul Huk, 37, of Ouldfield Close, Rochdale, was found guilty of sexual activity with a child.
The defendants come from a range of nationalities - Kendakumana and Chansa are from Congo, Abubaker is a Kurd, while Huk and Khan are believed to be of Pakistani heritage.
Several knew each other but it was not the prosecution case that they all acted in an organised manner.