Detectives hunting the killers of a young City lawyer stabbed to death yards from his Willesden home have issued descriptions of witnesses they want to trace.

Last Thursday night two youths viciously kept stabbing Tom ap Rhys Pryce, 31, even after they had taken his personal belongings.

Minutes earlier the killers were filmed as they robbed a second victim, an Asian man, on the platform at Kensal Green station.

CCTV cameras at the ticket gates captured the suspects exiting at 11.10pm. Fifteen minutes later Mr ap Rhys Pryce, on his way home from a party, followed unknowingly in their tracks.

As the Cambridge graduate approached the house in Bathurst Gardens he shared with his fiance, Adele Eastman, the robbers overwhelmed him.

Earlier that night he called her to say he would be home by 11.30pm, but just after midnight Mr ap Rhys Pryce was dead.

Police believe an Asian woman in a light coat have been on the same northbound Bakerloo train as the killers. The woman, who carried a rucksack and a suitcase, may have spotted them on the train or on the platform before she left the station.

Other possible witnesses seen on CCTV include an Asian man in dark clothes, a white woman wearing a grey coat and scarf, and a light skinned man. He was dressed in a navy blue jacket with a white logo on the left side of the chest, grey trousers and a dark hat.

After the 31-year-old Linklaters solicitor, three more people exited: an Asian male in a dark coat and suit; an Asian male with light headwear, a beige jacket and dark trousers; and a white woman wearing a pink hat and grey coat.

"If you recognise your description, please come forward," said Detective Superintendent Julian Worker. "You may feel that you do not have any information that would assist police but we still need to hear from you."

Police are also still looking for a man filmed on CCTV the morning after the murder as he tried to use Mr ap Rhys Pryce's Oyster card at Kensal Green Station.

Anyone with information can call 0207 247 7821.