One of the victims of a double murder may have been involved in an international internet betting scam, it emerged last night.

Two Chinese graduates may have been murdered because of their involvement in an internet betting scam and the trading of fraudulent documents, police confirmed last night.

Zhen Xing Yang and his girlfriend Xi Zhou, both 25, were found dead with horrific head injuries in their flat in the west end of Newcastle on Saturday.

Detective Superintendent Steve Wade, who is leading the investigation, said: "A possible motive for the killing is beginning to emerge concerning the lifestyle of Xi Zhou and Zhen Xing Yang.

"Community intelligence, supported by the examination of computer equipment and mobile call data, has shown both of the victims have been involved in fraudulent activity which has angered and upset a number of people. We are currently investigating this as a possible motive for the killings."

Mr Yang placed adverts on UK-based Mandarin- language websites recruiting people to watch football matches around the world. In one he wrote: "It is a very simple job, any student who is interested, please contact Zhen Xing Yang."

An advert posted under the name CICI-UK, his girlfriend's nickname, on a website last October, said: "Work: watch football games and send live information to people. Requirement: Basic understanding of football rules, no professional background needed, advantage if you have a car."

Northumbria Police confirmed officers seized a computer and three mobile phones from the murder scene. Detectives said examination of the computers, mobile phones and websites was ongoing.

However, it is emerging that Zhen Xing Yang may have been involved in internet betting scams and the arrangement of false and fraudulent documentation, such as travelling visas and professional qualifications.

There is evidence Mr Yang, known as Kevin, was tortured for up to an hour before he died from a combination of wounds. The couple's cat is also thought to have been drowned by their killers.