Police yesterday scoured the Tai Kok Tsui waterfront for a severed hand after a man revealed to investigators where he had dumped some of the body parts of his parents after they were killed.
The 29-year-old younger son of the couple was arrested on Friday in Western, along with another man, 35, in relation to the killing.
Police discovered the bloody remains of Chau Wing-ki, 64, and his wife, Siu Yuet-yee, 63, in a second-floor flat in the Hoi Hing Building in Kok Cheung Street on Friday.
The couple's older son, 35, had reported the couple missing six days earlier.
The heads of the couple were found in the fridge, while police recovered parts of three arms and four legs around the flat.
Their heads covered by black hoods, both suspects were yesterday taken to the scenes of the crime - the Tai Kok Tsui flat and a waterfront promenade near Hoi Fan Road - with investigators.
The waterfront area where some of the body parts were discarded is a 15-minute walk from the flat.
The suspects retraced their steps along a pebble-covered waterfront path near the Hampton Place residences, walking towards the promenade and the pier where the body parts were allegedly thrown into the water.
Chief Inspector Kwan King-pan, of the Hong Kong Island regional crime unit, said investigators had located most of the body parts but said a hand was still missing. "Somebody confessed to us that he dumped the remains here. It could be that hand," he said. A thorough search by divers would be carried out, he added.
Police are yet to determine a motive for the killings, which they believe happened on March 1.
The younger son initially told police his parents planned to visit the mainland when he had last seen them in Mong Kok on March 2, but police became suspicious when there was no record of them leaving the city.
Officers were able to identify the couple from their severed heads, but they want to carry out further DNA and fingerprint testing on the missing hand.
Other body parts were being analysed, and were proving hard to put together, Kwan said.
Bloodstains in the flat had been cleaned up and preservatives had been found with some body parts. It is understood the couple went to the flat after the younger son lured them there by saying he wanted to buy it.