Detectives investigating the murder of Mohammed Hussein in Edmonton on Monday 1 April have made a third arrest.
A 19 year old man has been arrested on suspicion of murder and is currently in custody at an east London police station.
Two men have been charged previously.
20 year old Natneal Tefsay of Park Road and Christopher Aluma, 18, of Foxglove Close appeared at Highbury Corner Magistrates' Court on yesterday charged with the murder of Mr Hussein.
They were remanded in custody to the Old Bailey on Tuesday, 9 April.
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Police arrived at the 73-year-old's home after Alfie chased a delivery man.
Officers believe the three assaults are linked and are appealing for information about the suspect.
Nine addresses in Lewisham were searched and 13 arrests made early on Tuesday morning in a planned, intelligence-led operation.