Detectives investigating the brutal murder of two Chinese graduates offered a reward of £5,000 for information.
Xi Zhou and her boyfriend Zhen Xing Yang, both 25, were found hacked to death in their ground-floor flat in Newcastle upon Tyne 13 days ago.
Detective Superintendent Steve Wade, who is leading the inquiry, said police remain desperate for information about the couple's last days.
The senior officer made a direct appeal to Britain's Chinese community at Charing Cross Road police station in central London, accompanied by a Mandarin and Cantonese-speaking translator.
Mr Wade said: "I am able to announce that a £5,000 reward is being offered for information which leads to the arrest and conviction of those responsible. Anyone with information about the murders of the two victims should contact Northumbria police on 08456 043 043".
Police said forensic experts had almost completed their examination of the murder scene at 8 Croydon Road in the city's West End. They have recovered hundreds of DNA, fingerprint and fibre samples as well as footprint evidence and other exhibits.
Thousands of hours of CCTV footage has been recovered from numerous public and private cameras around the address and was now being studied.
Police found the couple's mobile phones inside the flat and were examining their use to narrow down the timing of the killings and for fresh leads.
Mr Wade said: "Inquiries are continuing with police forces across the UK to establish if any links exist between the murders in Newcastle and any other part of the country. It is too early to give detailed information, but at this time we do not appear to have any similar murder inquiries throughout the country."
The detective said officers continued to hunt for a man who rented a room from the couple at the beginning of August.
