Pathologists believe the same kind of weapon was used in Saturday's attacks in which a Taikoo Shing man was killed and another was wounded.
But detectives who yesterday issued a sketch of a suspect said more evidence was needed to confirm there was only one attacker.
Senior Superintendent Tam Tak-wing said: 'Pathologists believe the wounds on the two victims were caused by the same kind of weapon, but we can't jump to the conclusion that it was the same man who committed both attacks.
'However, the possibility is one of our directions of investigation.' Mr Tam said the suspect was reportedly carrying a 25-centimetre-long curved knife when he fled from the scene at about 7.40 am on June 7.
Lie Shang-sien, 57, was stabbed four times in the back and died from having his throat slashed.
Poon Chi-yuen, 39, suffered a 10 cm-deep wound to the back of his neck after being stabbed near a Tai Koo MTR exit about a three-minute walk from the car park where Lie was killed.