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A total of seven people have now been arrested in connection with his murder.
Two men aged 34 and 18 were arrested at addresses in south London on the evening of 28th March - one on suspicion of murder, one on suspicion of possessing a firearm.
Five people were arrested on the morning of 28th March. All seven suspects remain in police custody at various police stations across London.
Mehmet Hassan was found dead in a house on Baxter Road on Monday.
A post-mortem examination took place on Wednesday, 26 March, at Whittington mortuary, which gave the cause of death as neck and chest injuries.
An incident room has opened under Detective Chief Inspector Andy Partridge, of the Homicide and Major Crime Command.
He said: "I would like to appeal to anyone who has seen any activity in and around this address to make contact with my officers. In particular I would like help from the public who can assist with the movements of the victim between 19.30hrs on Sunday (23 March) and shortly before police found the victim on Monday.