A RESTAURANT worker who slashed his pregnant sister-in-law's throat during a row was yesterday sentenced to death by the High Court. The mandatory penalty was imposed by Mr Justice Barnett on Tsoi Fai-kwong after a jury found him guilty of the murder of Mrs Tsoi Chan Sou-fong. Tsoi, 25, did not dispute killing Mrs Tsoi, 27, but denied murder and committing necrophilia. He had claimed provocation and self defence and that he had lost control of himself. The court heard evidence called by prosecutor Mr Toby Jenkyn-Jones that the Tsoi family operated a Chiu Chow restaurant. The business was run casually and no accounts were kept. Anyone needing money helped himself from the till. This practice came to an end when Mrs Tsoi, the wife of the eldest of the three sons in the family, Mr Tsoi Wai-lun, arrived in Hongkong from China to join the family. There was resentment that she, as an outsider, should take money from the cashier and this led to frequent quarrels. After a row on December 21, 1991, Mr Tsoi decided to leave the family business with his wife and also to move from the Hunghom flat where the family lived. When he returned home at about 9.10 pm two days later, he found his wife lying in a pool of blood in their room. The cause of death was a wound to her neck. A post mortem examination indicated the body had been sexually interfered with after death. After his arrest, Tsoi admitted he had long wanted to kill his sister-in-law. In his defence, Tsoi, represented by Mr Duncan Percy, told the court he accidentally opened the toilet door when Mrs Tsoi was inside. She was angry and scolded him, calling him a sex maniac and a peeping Tom, he said. She had also slapped him across the face and thrown a chair at him. A fight ensued during which she got hold of a chopper and he picked up a chair to protect himself, he said. He grabbed a chopper and held her in an arm lock. But when he relaxed his grip, he realised she was not moving, he said. Thinking he had accidentally strangled her, he panicked and lost control of himself, picking up the chopper and using it on her, the court heard. He then pulled down her trousers to make it look like a rape and robbery that had gone wrong, Tsoi told the court, denying he had committed necrophilia. A psychiatrist was called to testify that he found Tsoi a man of low intelligence who was mildly retarded and easily provoked.