A man suspected of bludgeoning a female neighbour to death with a crowbar while he burgled her Kwai Chung flat in March has died after fleeing to Japan, Hong Kong police said on Saturday.

Police were called to the property at 15 Kwai Yi Road on March 14 after the 63-year-old victim's partner returned home to find her dead from head injuries and the flat ransacked.

Detectives identified a man who lived on the same floor as their suspect, finding a pair of blood-stained sneakers in his home. They also discovered that he had taken a flight to Japan at 5pm the same day, before the case was reported.

Officers said five diamond rings, a mobile phone, a watch, five bank cards and a small amount of cash were missing from the flat. The stolen goods are worth $130,000.

The police say they believe the killer stole the spare key to the flat and attacked the woman after being caught while committing the burglary. A bloodied crowbar, thought to be the murder weapon, was found at the scene.

The force says it's been co-operating with Japanese law enforcement and was notified on April 6 that the body of a man had been found in the suburbs of Yamanashi Prefecture, near Tokyo, alongside a suicide note.

"Japan's law enforcement agency has recently confirmed the identity of the deceased and handed over the body to his family, Hong Kong police said in a statement. "Police have been following up on the developments and investigation is still under way."