A businessman was found guilty of murdering a family of four at their home in Wootton in April 2011.
Motivated by revenge, Du stabbed Jifeng "Jeff" Ding and his wife Ge "Helen" multiple times, leaving them for dead in the kitchen. He then went on and knifed their two daughters Alice, 12, and Nancy, 18.
"This was a brutal, shocking crime. Anxiang Du travelled to the Dings' home armed with a knife and killed the whole family in their own home," said Steve Chappell, the chief prosecutor.
The jury heard how Du "massacred" his former business partners the Dings in revenge after he lost a 10-year legal battle over a Chinese herbal medicine business they set up together.
"The evidence was clear that this was an act of premeditated revenge and Du knew what he was doing," he added.
ITV Reporter Rupert Evelyn reports:
Relatives of the Ding family said hearing about the murders was "like the whole sky had fallen down."
They learned more details about Du's horrific actions during the trial. "The evidence we heard in court was just like a knife to the body," Mrs Ding's father Zuyao Cui said.
Mr Cui said Du had not shown any remorse during the trial and added that the murders were premeditated, saying: "The fact he let himself in the back door, showed that it was planned."
The killer was able to flee the country after police mishandled a 999 call from one of his victims. Alice Ding made the call from her mobile phone as Du carried out the killings.
Jurors wept as they listened to a recording of the call. Both girls could be heard screaming before the line went dead.
Northamptonshire Police admitted to "badly mishandling" the call with officers being sent to the wrong address.
The bodies of the victims lay undiscovered for two days in their Northampton house. Du remained on the run for 14 months until he was captured in Morocco in July 2012.
The force admitted they will "never know what may have happened" if they had responded correctly to the call but said it was "unlikely" the Ding family could have been saved.