The attacked used a black Vauxhall Astra to flee the scene.
A newsagent who was stabbed to death during a burglary at his shop on Sunday has been identified as 54-year-old Ravi Katharkamar.
Mr Katharkamar, who was thought to have two children, was attacked as he opened his shop in Pinner, north west London, shortly before 6am.
A passerby had found him collapsed inside the show before police and paramedics were called to the scene but he was pronounced dead 45 minutes later. It was the second robbery at the shop within six months.
Formal identification took place by his next of kin following a post-mortem examination today. The cause of death was confirmed as a stab wound to the chest.
Detective Chief Inspector Simon Stancombe from the Homicide and Major Crime Command unit said: "This was a vicious and unwarranted attack on a completely innocent man. Ravi's attacker got away with a few pounds worth of coins, but he leaves behind a family utterly devastated and a close-knit community asking who could do such a thing.
"Help me catch the man who did this. The attacker fled with a shop till - have you found this discarded or seen someone in possession of a shop till who wouldn't normally have one? Do you know someone trying to use lots of loose change since yesterday morning?"