Dr Imran Farooq was on his way home from work when he was attacked outside his home in Green Lane, Edgware shortly before 5.30pm on Thursday 16th September 2010.
A post-mortem gave his cause of death as multiple stab wounds and blunt trauma to the head.
A five and a half inch-bladed kitchen knife and a house brick used in the attack were recovered at the scene.
Detectives from the Met Police Counter Terrorism Command remain committed to finding those responsible.
They believe his murder would have required careful planning and would have required help from other people, some of whom may have provided assistance or information unwittingly.
They want to speak to anyone who was asked for information about Dr Farooq and his routine.
More top news
Puppies and dogs have been rescued from an address in Dagenham, after being found in appalling conditions.
Dramatic CCTV footage has captured the moment a bus driver tackled a passenger to the ground in a street fight 'over the bus fare'.
Police are trying to track down a man who sexually assaulted a schoolgirl in Bethnal Green, after posing as a plumber to get into her flat