LONDON, August 12, 2008 (AFP) - Police probing the brutal murders of a young Chinese couple in Britain found a drowned cat in the flat where they were killed, they said Tuesday.

Xi Zhou and Zhen Xing Yang, both 25, were found with serious head injuries in Newcastle, northeast England, on Saturday by friends.

Officers admit they are baffled by the case -- chief investigator Detective Superintendent Steve Wade said: 'We are a long way short of establishing a motive for this crime and we are a long way short of arresting anyone.'

The pair both graduated from Newcastle University in 2006. Xi, who was working in a restaurant in the city, was originally from Hunan province in southeast China, while Zhen had family in Dalian, northeast China.

They both suffered severe head injuries caused by a knife and another sharp weapon, police say. Zhen also suffered extensive bruising to his forearms, likely caused as he tried to protect his head.

The black and white cat was found in a water-filled washing bowl under the bathroom sink with a towel and kitchen gloves on top.

'One possibility being considered is the cat has been killed by those responsible for the murders,' Wade said.

Officers have ruled out any link to gangsters or drugs.

The killing has triggered concern among other Chinese young people in the area, which has a large Asian community.

In June, two university students from France -- Laurent Bonomo and Gabriel Ferez, both 23 -- were found dead in Bonomo's apartment in New Cross, southeast London after being bound, burned and repeatedly stabbed.