A killer who massacred a family of four was able to flee the country after police mishandled a 999 call from one of the victims, leading to a manhunt lasting more than a year.
Anxiang Du was on the run for 14 months after he stabbed Manchester Metropolitan University lecturer Jifeng "Jeff"' Ding, his wife, Ge "Helen" Chui, and their two daughters, Xing "Nancy", 18, and Alice, 12, on April 29 2011.
Their bodies lay undiscovered for two days in a four-bedroom detached house in Pioneer Close, Wootton, Northamptonshire, despite a frantic 999 call being made from Alice Ding's mobile as Du carried out the killings.
Northamptonshire Police have admitted they will "never know what may have happened" if they had responded correctly to the call, made at 3.32pm, in which both girls could be heard screaming before the line went dead.
The call was found to have been "badly mishandled" by the force, resulting in officers being sent to the wrong address and the emergency call closed when nothing untoward was found at that location.
An investigation by the police watchdog, the Independent Police Complaints Commission, later said:
"Had police used more detailed checks and a mapping system available to them, the need for a subscriber check would have been established, the correct address in Pioneer Close would have been identified and in all likelihood attended by officers within minutes."
Northamptonshire Police have said it was "unlikely" the Ding family could have been saved, but admitted it was possible that Du could have still been at the address if officers had been dispatched to the right location.
The trial heard from pathologist Guy Rutty, who told jurors the family would have died of their stab wounds shortly after they were inflicted due to the blood loss.
However, jurors also heard that Du remained in the Northamptonshire area until late evening.
Du told a psychiatrist after his arrest that he lay down and slept in the Dings' house after carrying out the murders, before leaving under the cover of darkness, taking the family's car.
The silver Vauxhall Corsa was captured on camera at Northampton services off the M1 just before 10pm on April 29.
From there, Du drove to London and the next morning boarded the 8am coach from London Victoria to Paris Gallieni, before travelling on through Spain to Morocco.
The bodies of the Ding family were not discovered until two days later, on the evening of May 1.
Neighbour Jason Horsley reported that he had seen a body lying on the floor through the back window of the Dings' home.
It came hours after officers from Northamptonshire Police visited the property, unaware of what was inside.
They had been asked to visit the Dings by West Midlands Police, who were looking for information in their search for Du, who had been reported missing.
Du's wife had contacted them after he failed to return from work. She told the force of a civil dispute between the two families but not of any threat.
As a result, officers visited the Dings' house at 8.10am on May 1 to ask whether they had seen or heard from Du. When there was no reply, they simply posted a card through the letterbox and left.
Hours later, Northamptonshire Police received the call from Mr Horsley and the grim discovery was made, sparking a manhunt that would last for 14 months.
Speaking after the trial, Detective Superintendent Tom Davies, senior investigating officer, said:
"We don't know what may have happened had we responded correctly (to the 999 call).
"We certainly recognise that when we had the 999 call that wasn't responded to properly that that was an opportunity for officers to be deployed to that address.
"Whether or not those officers would have found Anxiang Du at the address is open to debate. It was important for us as an investigation team to simply focus on finding him.
"In any homicide investigation we'll always face challenges. In life we all make mistakes. It was important for us to realise that, once those mistakes had been made, we then focused on the positives and worked with law enforcement to find him."