The city's fourth murder case in a week emerged yesterday when an autopsy revealed strangulation marks and a head injury on a housewife who was thought to have committed suicide alongside her husband.
Lau Wai-yan, 35, and her unemployed husband, Fung Wing-fai, 38, were found dead in bed beside a tray of charcoal ash at their Kwai Chung flat on Tuesday night. Two dead cats were also found in the flat.
A murder-suicide investigation was launched by the Kwai Tsing district crime squad after an autopsy yesterday morning found pressure marks on Lau's neck and the injury to the back of her head.
The decomposing bodies were discovered after a friend visited their flat in Kwai Tai House, Kwai Fong Estate. He called police when no one answered the door.
Officers said there was no sign of a struggle and in a statement on Wednesday reported that an initial investigation did not suggest any foul play. The couple were thought to have been dead for five to six days. No suicide notes were found.
"A forensic pathologist found signs of squeezing on [Lau's] neck," said Chief Inspector Chan Tai-wai. "There was also an injury on the rear of her head. It was probably caused by a blunt object."
Police now believe the woman passed out after being attacked by her husband. He then lit the charcoal to kill them both by carbon monoxide poisoning.
But Chan said the cause of death had not been established and further tests were needed.
A police search failed to uncover an object that may have been used as a weapon in the flat.
Fung was found to have bought a bag of charcoal from a supermarket. Chan said police were investigating whether the couple had financial difficulties or a relationship problem.
The case comes after two gruesome murders and a murder-suicide.
On Sunday, Wong Suk-kan, 47, hacked her tycoon lover to death before leaping from a Kowloon West apartment block. Her lover, Peng Chi-hui, 49, also known as "King of Fruits", was a Nanhai district member of the Chinese People's Political Consultative Conference in Foshan.
Police's figures show there were 27 reports of homicide last year, up from 17 in 2011.