Kan was detained by police on May 4 after returning to Shenzhen. He allegedly confessed that he had killed the pair in May 2000 in one of two adjacent flats he rented and had hidden the bodies in the other one.

According to the Kan had been renting the top-floor flats since 2000 at a residential block in Buji, about 15 minutes' drive from the Luohu checkpoint.

Kan told the landlord one flat was used for accommodation and the other as a utility room.

Last month, at Kan's request, his landlord sent a maid to clean the flat used as living quarters. After cleaning that flat, the helper mistakenly walked into the other flat and discovered a bag of bones under the bed. The bones were wrapped in plastic and placed inside a polypropylene bag.

According to the newspaper, Kan met his mistress, a migrant worker then in her 20s, in the district. They had a son in 1998 and Kan had set aside 2,000 yuan a month for his Shenzhen family - on top of supporting his wife and two children in Hong Kong.

Although he had a stable job, Kan had a gambling addiction and could barely support himself. Driven to cut his losses, and hundreds of thousands of yuan in debt, he allegedly told police he strangled his mistress and son while they were taking a nap after lunch.

The slain woman's family said they did not realise she was missing until last month, thinking only that she had lost contact after moving in with Kan.

The newspaper also found that Kan ran a notice in a local paper of his divorce from his Hong Kong wife, after she fled their home with their two children.

Kan's mother said she lost contact with him in 2004 and was shocked to learn he had been detained for murder. "I helped him clear HK$300,000 of his debt. I've got no idea what he's been up to these past 10 years. He was timid," she told the "Please help me check if he committed the crime."

According to a local media source, Kan had been working at a warehouse in Hong Kong for the past few years.

"Kan rented the two apartments because they are on the top floor of a remote building that was close to a garbage refuse site. Few people would venture upstairs and the refuse site would also mask the odour from the bodies," the source said.

Like most tenants in the building, Kan paid rent every three months. Tenants said they seldom saw him and knew nothing about him. "I didn't know there was a Hong Kong man living upstairs until the police came and sealed the flat," a resident said. "It's so horrible."

Buji, a satellite town on Shenzhen's northern outskirts, was coined "Little Hong Kong" when it became a booming "mistress village" in the 1980s and 1990s, housing the mainland girlfriends of many cross-border drivers and office clerks from Hong Kong.

A younger brother of Kan, who lives in Sheung Shui, told the that the family would "handle the matter appropriately" and that "what needed to be done has already been done".