A young couple were victims of a "cold-blooded murder" when masked men armed with a shotgun killed them in their home.
The couple had moved in together just before Christmas
Jordan Jackson, 20, was found in the hallway of the flat in Menlo Gardens, Upper Norwood, south-east London. He had been shot in the neck.
Leyla Djemal-Northcott, 21, was shot in the head as she lay in bed.
Mr Jackson's twin brother, Kieran, was also shot on Tuesday and remains under armed guard in hospital.
Another woman has been treated for shock.
Police said the two gunmen fired at least six shots during the attack at about 0640 GMT.
The first suspect is described as a dark-skinned black man, about 6ft (1.8m). The second suspect is described as a lighter-skinned black male about 5ft 5ins (1.67m).
Mr Jackson, a removals man, had been in a relationship with Miss Djemal-Northcott, a post office worker, for about five years.
They had moved into the flat together just before Christmas last year.
Det Supt Gary Richardson said: "It is a cold-blooded murder.
"We would urge anyone [who] was in the Beulah Hill area of SE19 or Menlo Gardens and saw two black men acting suspiciously or saw two men decamping from the scene on foot or by vehicle to contact us."