No further action will be taken against a teenage boy arrested over the murders of Greater Manchester police officers Fiona Bone and Nicola Hughes.
The 15-year-old was held following the deaths of PC Bone and PC Hughes, who were lured to their deaths in Mottram on 18 September.
One-eyed fugitive Dale Cregan has been charged with their murders and also with the murders of father and son David Short and Mark Short.
It is understand the men died as a result of a long-running feud between Manchester's notorious crime families.
Assistant Chief Constable Steve Heywood said: "We remain committed to fully investigating the circumstances surrounding the murders of PC Fiona Bone and PC Nicola Hughes.
"As we have said previously, this remains a complex and sensitive investigation and we continue to ask the public to search their conscience and urge anyone who has any information to contact us."
There was anger that Cregan could evade capture for months, despite a huge reward of £50,000 being offered for his capture.
The 29-year-old turned himself in to police shortly after the incident.
Soon after, sick fan pages began to appear on Facebook that called Cregan a 'hero.'
The murder of PCs Hughes and Bone sparked an outpouring of grief from members of the police force.