A gang of men were convicted today of a catalogue of offences against vulnerable girls who were preyed on and abused.
The group of men befriended the girls, plied them with alcohol, then took them to "parties" where they were often used for sex.
An undercover investigation by Derbyshire Police, dubbed Operation Retriever, was split into three trials which have run since February.
At the culmination of the third case today, two of the gang's ringleaders received more convictions for sex crimes at Leicester Crown Court.
Thirteen men were charged in relation to Operation Retriever and 11 stood trial for a string of charges - not all sexual - relating to the case, which involved 26 victims, one as young as 12.
Out of the original 13, a total of nine stand convicted today.
At the opening of the first trial, held at Nottingham Crown Court, prosecutor Yvonne Coen QC said: "They preyed on young girls who were vulnerable, either because of their age and because of their own personal circumstances.
"They exploited these girls either for their own sexual satisfaction or for their friends."
Abid Mohammed Saddique, 27, and Mohammed Romaan Liaqat, 28 - both married with children - were said to be the leaders of the gang.
Saddique, of Northumberland Street, Normanton, Derby, was convicted of four counts of rape as well as two counts of false imprisonment, two of sexual assault, three charges of sexual activity with a child, perverting the course of justice, and aiding and abetting rape.
Liaqat, of Briar Lea Close, Sinfin, Derby, was found guilty of one count of rape, two of sexual assault, aiding and abetting rape,affray, and four counts of sexual activity with a child.
Both pleaded guilty to causing a person under 18 to be involved in pornography.
They will be sentenced on January 7.
Other defendants have already been convicted and sentenced.
Akshay Kumar, 38, admitted one count of causing a person under the age of 18 to be involved in pornography and was jailed for two years and 10 months.
Faisal Mehmood, 24, pleaded guilty to sexual activity with a child before the trial and was jailed for three years.
He has now been deported to Pakistan.
Mohammed Imran Rehman, 26, was jailed for seven-and-a-half years after being found guilty of rape, while Graham Blackham, 26, was given a three-year sentence after he was convicted of two counts of breaching a sexual offences prevention order.
Liaqat's brother Naweed Liaqat, 33, and Farooq Ahmed, 28, pleaded guilty to perverting the course of justice and were both jailed for 18 months.
Ziafat Yasin, 31, was cleared of sex charges but pleaded guilty to being concerned in the supply of cocaine.
He was jailed for three years.
In echoes of a similar case in Rotherham earlier this month, juries were told the victims were mostly schoolgirls, some estranged from their families and homes.
But police said today they were from a variety of backgrounds and urged all parents to be aware of the risks of sexual exploitation.
The court heard that victims were targeted predominantly by Saddique or Liaqat, who embarked on a "campaign of calls and texts", then plied them with cigarettes, alcohol, drugs and "sometimes a ride in a flash or sporty car".
Once they met up, the girls were forced to have sex with, or perform sex acts on, various people, the court heard.
"The girls involved in the case were young and however cool and grown-up they may have wanted to be or intended to appear, in fact they were naive and impressionable," Ms Coen said.
"The reason for the main defendants' relentless pursuit of the girls in this way was quite simple. They wanted sex, whether the girls wanted sex or not."
One of the girls told the court about a time she was raped in June 2008, when she was 16.
She knew one of the men who called her asking to meet up and, after being taken to a petrol station to buy alcohol, she was driven to an isolated spot where one of the men raped her.
"It felt like it lasted for hours but it didn't, I know that it didn't," she said. "While I was lying there, he said 'Do you like it, do you like it?'. And I said yes.
"I tried to do everything I could to stop it so at that stage I just said yes. I just thought if I tell him what he wants to hear, it will be done quicker."
Police said the youngest victim was just 12 and the eldest was 18. Today convictions were achieved for 15 of the victims.
Detective Superintendent Debbie Platt, from Derbyshire Police, said the investigation was launched in January last year after intelligence from Staffordshire Police, prompting the undercover investigation.
"We were really shocked with the scale and extent of what we'd uncovered because people won't appreciate but this is a very hidden crime so we hadn't got a victim coming forward and saying what had happened, so we've had to investigate without the victim sometimes knowing what we were doing," she said.
"We were targeting the perpetrators to find out what they were doing and what was happening.
"These are sexual predators, they've deliberately targeted vulnerable young girls and they've used the classical grooming process, which is they've driven cars round the city, cruised round the city streets, pulled up at the side of girls who are clearly young.
"They've chatted them up, they've got their first name, they've got their mobile phone number, they've then texted them, they've offered them sweets, they've offered them alcohol, they've offered them a drive in a vehicle and they've taken them to various parties in the city."
Counsel for Saddique have already applied for leave to appeal against previous convictions.
After today's case, Judge Philip Head explained the context of the case to the jury and the previous trials and convictions.
Speaking after the case today, Detective Inspector Sean Dawson, deputy senior investigating officer, said: "These convictions have brought an end to a lengthy and complex investigation that has been brought to court thanks to the bravery of the victims in this case.
"These two men are predatory sex offenders who, with their associates, have systematically abused and raped teenage girls.
"We are shocked by the scale of abuse we have uncovered and the impact it has had on the girls who were the victims of these callous men.
"Child sex exploitation is something that parents and carers across the country should be aware of.
"Parents and carers should talk to their children, take an interest in what they are doing and warn them not to go off with strangers, no matter how tempting it might seem.
"All responsible members of our society must do everything they can to combat child exploitation of any kind."
CPS reviewing lawyer Samantha Shallow said: "This is a shocking case of persistent targeting and sexual abuse of young, vulnerable girls and women over a sustained period by a group of criminals.
"Abid Mohammed Saddique and Mohammed Romaan Liaqat and their associates were sexual predators who have targeted the victims because of their age and vulnerability.
"The scale of their criminality against those they preyed upon is simply shocking."