The two Chinese students murdered in their flat near Newcastle University were hard workers who had graduated with good degrees, police said yesterday.

The bodies of Xi Zhou and her boyfriend, Zhen Xing Yang, both aged 25, were discovered in separate bedrooms of their home in the West End of the city. Detectives said that the murder scene was gruesome. Both had suffered severe head injuries inflicted by at least two different weapons. Mr Yang had lost a lot of blood and Ms Zhou may have been suffocated.

There was no sign of forced entry to the ground-floor flat and police believe that the couple may have innocently welcomed the killer — or killers — into their home.

Each was attacked with a knife and another sharp-edged instrument. They may have been dead for more than 24 hours before their bodies were found on Saturday afternoon. No murder weapon has been recovered.

The couple were international students at the university. Both had graduated in September 2006.

Ms Zhou, who was known to her friends as Ci-Ci, was awarded an MA in applied linguistics and had been working as a waitress at a restaurant in the city centre for the past 18 months. Detective Superintendent Steve Wade, of Northumbria Police, said that she was described as a reliable, hard-working member of staff who had a bubbly personality and was a joy to work with.

The dead woman’s parents, who were traced to Hunan province in southern China, have been informed of her death. Police have been unable to find any relatives of Mr Yang, who gained an MA in international human resources.

Chen Ying, a cousin of Ms Zhou, said that Mr Yang came from the city of Dalian in northeastern China, and had been in the process of setting up his own business in Newcastle.

Mr Wade said: “They were two nice, hard-working, respectable people who have come to the UK for the best of reasons, to get a good education. We have no known motive for this savage and brutal attack.”

Ms Zhou was last seen when she left work at 3.50pm on Thursday. Staff at the Wagamama restaurant, where she worked, were surprised when she did not turn up the next day.

Mr Wade said that officers were called to the flat, which is in an area with a substantial ethnic minority population, after an emergency call was made by the couple’s friends. They had visited the flat on Saturday and when there was no answer they gained entry through an unsecured downstairs window. They found Ms Zhou’s body in the front bedroom and that of Mr Yang was found in the back bedroom.

Mr Wade described the killings as “savage and brutal” and said that the crime scene was one of the worst that he had seen in his career. Each had suffered defence wounds. “Given the amount of blood, someone has come home bloodstained. Someone must know something out there,” he said.

The last known contact with Mr Yang was a brief phone conversation with a friend last Wednesday in which she found no cause for concern.

“There is no sign of forced entry,” Mr Wade said. “We believe whoever was in the flat was known to the victims or had been let in.”

Xin Yang, a University of Newcastle student, said that more than 200 Chinese students lived in the West End but some were now thinking of moving elsewhere.

Eddy Tang, of the International Christian Fellowship in Newcastle, said that several members of his congregation had known the dead couple. “They were friendly, hard-working and popular. The mood in the community is very subdued. They are in mourning.”

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