'It sounds reasonable to have an inquest.'

Andrew Lam, chairman of the Criminal Law Committee of the Law Society, agreed. 'Common sense says that when a dead body is found and the circumstances surrounding the death were dubious, you would call upon an inquiry of some sort to see if there was foul play,' he said.

However, he conceded that in Pang's situation, where the woman had been dead for four years before the discovery of her body, a coroner might not be able to find a cause of death as there might not be any witnesses.

Mr Lam did not believe the Pang family would succeed if they decided to seek a private prosecution.

'Unless they have sufficient evidence, they won't succeed. The requirement of evidence proved is the same as public prosecution - beyond reasonable doubt,' he said.

'For a murder case of six years ago, they will need forensic evidence - DNA of the killer, a witness to the murder, confession of a killer or a motive as to why the victim would be eliminated.

'But motive itself is not sufficient,' Mr Lam said.

'They will also need evidence a suspect appeared at the crime scene, someone heard screams from the crime scene, followed by a suspect leaving the scene and the discovery of the deceased. But here, it's years later that the body was discovered in someone's flat.'

Seeking a judicial review would also be difficult due to the delay, said Eric Cheung Tat-ming, assistant law professor at the University of Hong Kong.

'In general, if one is to seek a judicial review against a decision of a public body, one has to institute the judicial review proceedings within three months of the decision but it has been four years since the Coroner's Court refused to entertain the request.

'Unless the court rules there is good reason for the delay and there has not been any prejudice as a result of the delay, the court will simply refuse on the grounds of delay,' said Professor Cheung.

Legislator and solicitor James To Kun-sun said that despite the suspicious circumstances, the Pang family did not have a case for an inquest. 'If the police feel it's a murder case and have a suspect, then an inquest in open court will simply alert the suspect into disappearing,' he said.

Another option for the Pang family was to lodge a complaint with the Independent Police Complaints Council if they were not happy with the force's investigation, he said.