An 18-year-old man has been arrested on suspicion of murdering two sisters in a park in London.
The bodies of Nicole Smallman, 27, and Bibaa Henry, 46, were found at Fryent Gardens in Wembley on 7 June, two days after a birthday party in the park.
Post-mortem tests revealed they died from multiple stab wounds.
Their family has been told in person about the arrest, the Met said. The arrested man from south-London was taken into custody where he remains.
The sisters had met friends in the park at about 19:00 BST to celebrate Ms Henry’s birthday.
The group had been in an area of Fryent Gardens which was about a five-minute walk from the Valley Drive entrance.
Extensive forensic work has been carried out at the park but smaller searches in outer areas continue, police said.
More than 1,000 exhibits including property belonging to Ms Smallman and Ms Henry have recovered and hours of CCTV collected, the Met said.
Det Ch Insp Simon Harding, said: “Given the significance of this development, we visited the family in person today to inform them of the arrest.
“Our thoughts remain with them at this very difficult time.”
The Met is appealing for anyone with information to contact them.