The 17-year-old girl and the 28-year-old woman stabbed in a house in south London are sisters, police said.
The elder sister died as a result of her injuries. Speaking at Brixton Station this afternoon, Detective Inspector Will Reynolds said:
"The lady who was fatally stabbed is the sister of the 17-year-old girl who tried to protect her."
The teenager suffered stab wounds to her head and hands.
More top news
The jury was shown footage of Rurik Jutting talking to the camera about rape, torture and murder, with one of his victims in the background.
An 11-year-old girl was sexually assaulted in broad daylight attack in a cemetery, police said.
Four people have died in an incident at an Australian theme park.