During the reign of convicted killer Colin Gunn on a Nottingham estate, a breed of unofficial policing took over in a part of the city.
Colin Gunn dragged down Nottingham's reputation
Throw in the problem of corrupt police officers and the force had to entirely re-think the way it operated.
Nottinghamshire Police faced one of its biggest ever challenges in bringing down the city's self-styled Godfather of Crime.
So how did the police reclaim the Bestwood Estate, and what happens now?
Nottinghamshire's Chief Constable Steve Green said Colin Gunn's influence on Nottingham left the city with a terrible reputation.
He said: "Gun crime started in Nottingham in 2000, but at that time it was largely confined to the African-Caribbean community around St Ann's, the Meadows and Radford.
"When the problem seemed to escalate in 2002, it was clear to us that something else was happening, there was a different dynamic.
"I think we saw something far more evil, far more insidious taking place in the white community in North Nottingham that required a different approach."
That different approach came in the form of a highly confidential operation to "decapitate Gunn's organisation".
"We took the view the sooner he was gone, the better," said Mr Green. "His was a classic gangster-type organisation that needed bringing down.
"What singled him out from any range of drug dealers was that he killed people, shot people and intimidated them in numbers that were far, far greater than anything else that we were experiencing.
"We now know, having taken away that regime, the massive impact he had on the locality he came from in Bestwood."
Nottinghamshire Police called in outside help to deal with the problem.
"We had to gather allies together to carry out this operation," said Mr Green. "We did not do it on our own, we did it with the help of the National Crime Squad, with Customs and Excise and Lincolnshire Police.
"Without those allies, we were never going to be able to bring the problem under control satisfactorily."
Lincolnshire Police were the ones to arrest Colin Gunn in 2005 after a "tremendous inquiry" into the Stirland murders. The murders of Joan and John Stirland in Trusthorpe in Lincolnshire in August 2004 were masterminded by Colin Gunn.
Fletcher and Parr were found guilty of corruption in 2006
He organised their killings in revenge for a murder carried out by Joan Stirland's son Michael O'Brien in Nottingham in 2003, and was jailed for life in 2006.
But for years Colin Gunn managed to stay one step ahead of the law. Two former police officers, Charles Fletcher and Philip Parr, were found to be feeding information through to Gunn and his organisation.
Det Supt Russ Foster, who was in charge of catching the corrupt officers, said Dc Fletcher was quickly identified as a culprit.
He said: "There were more than 40 officers working on this operation on off-site premises, everything was extremely confidential. We needed to make sure there weren't any internal leaks..."
It was the most confidential operation ever run by Nottinghamshire Police, with calls between Fletcher and the criminals being monitored, and Fletcher himself the subject of sophisticated surveillance techniques.
The force has now brought in stricter vetting procedures and has a unit dedicated to stamping out corruption within the force.
Mr Foster said the corruption episode went "against the grain in terms of what policing is about. It also has the potential to undermine public confidence".
Restoring public confidence is top of Ch Con Green's agenda.
He said: "I think we'll never know how much damage the corrupt officers did." He said the police would be around the Bestwood Estate "for as long as they needed to be".
"A measure of the public's confidence is that they're starting to report crime to us and a key indicator is that people are starting to request to live on the Bestwood estate again.
"It has been a relief ever since the day Colin Gunn was arrested. We all take a degree of pride and professional satisfaction in what has been achieved and what we accept is that this has been a traumatic chapter in the history of the city.
"Our determination is that it must never happen again."