“Police were called at 12.16pm to reports of the incident and on arrival officers found Dada administering CPR to Katrina.”
Paramedics and London’s air ambulance attended but pronounced Ms Makunova dead at the scene shortly afterwards on 12 July 2018.
Dada pleaded guilty to manslaughter on the first day of his trial at the Old Bailey on Wednesday and will be sentenced later this month.
The court heard how Dada and Ms Makunova had been in a relationship that had recently deteriorated.
A series of social media messages between the pair on Ms Makunova’s mobile phone “showed there was a feud between them, with both parties making veiled threats and insulting each other”.
Ms Makunova had gone to the block of flats on Brisbane Street where Dada lived, with the knife in her handbag, on the day she died.
“The pair encountered each other on the ground floor and a struggle began,” police said.
Dada was initially arrested on suspicion of murder but subsequently charged with manslaughter as the investigation progressed.
The teenagers murdered in London in 2018
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Detective Inspector Domenica Catino said: “A young woman has lost her life and my thoughts are with her family and friends, who have been devastated by Katrina’s death.
“This is another young person who has been killed as a result of a knife and we need our communities to work with the police to end this scourge.”
The total of 134 homicides recorded in the year was the capital’s highest total since 2008, which saw 154 people killed, and a 15 per cent rise year-on-year.
Metropolitan Police Commissioner Cressida Dick had named street violence as her “number one priority” and acknowledged the last 12 months had been “challenging”.
At an end-of-year briefing with journalists, she said there had been a rise in domestic killings but that the number of young people being stabbed in public had fallen.
“We’re trying our very hardest to reduce violence on the streets as much as we can,” Ms Dick said.