Two men seen carrying out a robbery at a railway station are being sought by police hunting the killers of City lawyer Thomas ap Rhys Pryce.
Thomas ap Rhys Pryce was recorded at a Tube station
Scotland Yard said the pair were caught on CCTV at Kensal Green train station approaching an Asian male before robbing him of a mobile phone and cash.
They left the station about 15 minutes before Mr Rhys Pryce, 31.
Soon after he was mugged then stabbed just yards from his Willesden home in north-west London, on Thursday night.
Mr Rhys Pryce's attackers had already robbed him before killing him as he tried to get away.
One witness heard him tell his attackers "You've got everything" but they went on to stab him, police said.
The Cambridge graduate was stabbed in his body, hands and head, suffering fatal wounds to his chest in what police have called a "gratuitous" attack.
Mr Rhys Pryce is thought to have tried to defend himself
The pictures from the station show two men carrying out the robbery on the platform at about 2305 GMT.
Scotland Yard said they wanted to talk to the two robbers to eliminate them from the murder inquiry.
They were black, wearing dark clothing with hooded tops and aged in their late teens to early 20s. One was slim and the other was described as medium build.
Det Supt Julian Worker said it was possible the pair had tried to rob others before the station robbery.
Police have also released CCTV pictures of Mr Rhys Pryce leaving the station.
Det Supt Worker added: "The assault on Tom was a particularly vicious attack - the suspects had already obtained property from him and still went on to inflict quite horrific injuries."
He was returning home after a night out with colleagues from the law firm where he was an associate.