Shortly after 4.30pm on Saturday, August 9, the bodies of Xi Zhou and Zhen Xing Yang were discovered at the home they shared on Croydon Road.

Today police are in a position to reveal the last known mobile phone conversation of her boyfriend Zhen Xing Yang.

Officers now know that Zhen Xing Yang made a call from his mobile phone at 12.42am on Thursday, August 7.

The final call from his mobile phone was made to a mobile number which police are currently checking alongside billing records.

Meanwhile, ITN is reporting that Mr Yang may have been mixed up in an online betting scam and tortured before his death - but police have not confirmed whether they are pursuing that particular line of inquiry.

Detective Superintendent Steve Wade, leading the investigation, said: "We are keen to speak with anyone who may have been in contact with either of the two victims in the days before their deaths.

"We are currently checking mobile phone records in order to tie down times of death and it would be of assistance to us if those people who spoke to them could contact us.

"We have recovered a number of mobile phones at 8 Croydon Road, but would like to know if there are any more mobile telephone numbers which people have for the couple."

In another aspect of the investigation, Northumbria Police has been liaising with the Metropolitan Police in order to gain support with translation services and with forces across the country on elements of the case.

Det Supt Steve Wade concluded: "Our officers have the support of forces across the country in their efforts to bring the killer or killers of Xi Zhou and Zhen Xing Yang to justice.

"I am asking anyone with information about the deaths to contact my officers, on 03456 043 043."

Meanwhile, police have released a video of the couple shot recently in the hope it will convince witnesses to come forward with information.