'He left home as a perfectly healthy child, and the next moment we saw him lying in a hospital morgue. How could we possibly take it?' he said.

Mr Wang said an autopsy on Friday had indicated that his nephew might have died from bleeding as a result of blows to the head, but the complete autopsy results would not be available for three weeks.

Describing him as a standout child with a good character, Mr Xia was quoted as saying that the wounds might have resulted from a fall during the night.

The international school is the most prestigious boarding school in Urumqi, and each of its five dormitories has a live-in teacher.

Mr Wang said they suspected something was wrong with the child a day earlier because one of his nephew's room-mates told the family that the boy had been knocking on the resident teacher's door, crying for help with stomach pains at about 2am on Thursday, but the teacher did not open the door.

He was escorted back to his dormitory by two other room-mates but left again just after six o'clock that morning and never returned.

'We don't know what exactly happened from then to the point when we were informed,' Mr Wang said.

He said they were particularly angry because the school initially reported that the child had died of natural causes and was trying to cover up the real cause of death by producing identical written testimonies from five teachers.

Police and education authorities decided to step in only when the family set up a shrine at the school in an attempt to seek justice.

Mr Wang said they had since removed the shrine and left.

'Our goal is very simple, and that's [finding] the truth.'