A businessman suspected of murdering a family of four travelled to the victims' home just a day after losing a bitter court battle over their shared business interests, it has emerged.
Northamptonshire Police said Anxiang Du, who has still not been traced, was now known to have caught a train from Birmingham to Northampton last Friday, when the family are thought to have been stabbed to death.
Mr Du (52) has been named as a suspect by detectives investigating the murders of university lecturer Jifeng Ding, his wife Helen and their two daughters.
Releasing CCTV images showing Mr Du at both Birmingham New Street and Northampton railway stations, Detective Superintendent Glyn Timmins confirmed that the businessman felt he was owed tens of thousands of pounds by Mrs Ding.
Mr Timmins said officers had also established that Mr Du caught a bus from Northampton to Wootton, where the Ding family lived.
Explaining the links between the ssuspect and the victims, Mr Timmins said the business relationship between Mr Du and Mrs Ding was being explored as the “primary motive” for the killings.
The detective added: “Clearly there was a dispute over a considerable amount of money related to a business that ended up in the civil courts.
“I think there was a suit and a counter-suit and at some stage I believe that the judgment went against Mr Du, or at least he hadn't received the money that he felt he was due. That is the motivation that we are exploring.”
Mr Timmins, who confirmed that the final court activity was thought to have taken place last Thursday, said Mr Du, who was carrying a yellow Adidas rucksack, was seen at New Street station at 11.22am on the day of the Royal wedding.
Further footage showed that he was in Northampton by 12.35pm and the family, whose bodies were found in separate rooms, are believed to have been killed later that afternoon.
Dr Ding, who worked at Manchester Metropolitan University, his wife, a part-time teacher, and their daughters all died from stab wounds.