A £10,000 reward is on offer for information leading to the conviction of those responsible for the murder of Alec Christopher in June this year.
Mr Christopher, 62, was killed at 6.50am in Avenue Road, Southall, on June 20. A CCTV camera caught Mr Christopher in Avenue Road rubbing and dabbing his hands. Police believe the pictures were taken just after the attack had taken place.
When he was found, near the junction of Avenue Road and Cambridge Road he had 'defence wounds' on his hands. The camera also caught a woman, possibly in her 40s, walking in the same direction as Mr Christopher.
DCI Norman McKinlay of the Serious Crime Squad said: "We would very much like to speak to the woman caught on CCTV. She may have seen something that could provide us with fresh intelligence, or she may have had a short conversation with Mr Christopher."
He added: "We would also like to speak to any other witnesses to the stabbing that have not yet come forward, or anybody that saw Mr Christopher collapse moments after the stabbing. Finally we want to speak with anyone who has any knowledge of who committed this assault."
Information to 8247 7821.