Two sisters found dead in a park after a party nearly a week ago were murdered by a stranger, police say.
Nicole Smallman, 27, and Bibaa Henry, 46,
They had met friends in the park at about 19:00 BST last Friday to celebrate Ms. Henry’s birthday.
A pond and tonnes of rubbish, which may contain vital evidence, are being searched by police.
The sister’s bodies were found shortly after 13:00 on Sunday and post-mortem tests revealed they both died from multiple stab wounds.
Det Ch Insp Simon Harding said on Friday: “We can now say with some certainty that Nicole and Bibaa were murdered by someone who was unknown to them.”
He said investigators were searching a large area, including a pond, and trawling through hundreds of thousands of tonnes of rubbish which may contain evidence that was accidentally cleared from the scene.
“We believe the suspect received injuries during the incident which have caused significant bleeding,” he said.
“Do you know anyone who has been wounded in the last week who is unable to account for their injuries?”
Police believe the killer left the park via the Valley Drive entrance.
The sisters and their friends had been in part of a park which was about a five-minute walk from the Valley Drive entrance to the park.
Mr. Harding also urged anyone who was in the park on Friday evening through to Sunday lunchtime and saw the group or noticed anything suspicious to come forward.
Extra resources have been brought in to help the investigation from across the Met, including additional detectives.
A 36-year-old man arrested in south London on suspicion of murder was released with no further action.