Photos: 21-Year Old Nigerian In UK Allegedly Kills Girlfriend For Breaking Up With Him

Five police officers face a probe into how they dealt with a series of complaints from a 17-year-old girl who said she was being harassed by her 'county lines' drug dealer boyfriend who went on to kill her.

Katerina Makunova was killed by Oluwaseyi Dada, 21, in Camberwell, south London, on July 12, 2018 - a day after she told her family she was ending the abusive relationship.

Previously, the trainee hairdresser and her family had called police five times between February and June to accuse Dada, who she met on Instagram, of assault and harassment.

The Independent Office for Police Conduct is examining the performance of two Metropolitan Police sergeants and three constables after the victim's family criticised the way they had handed their complaints, reported The Times.

Ms Makunova died after an altercation in the foyer of Dada's block of flats in Camberwell. Police believe this ended with her falling on her handbag which contained a knife that fatally pierced her chest.

Dada, from Streatham, a Nigerian, admitted manslaughter, but Ms Makunova's family believe he should have been charged with murder due to his controlling and brutal behaviour.

Brett Weaver, prosecuting, said there was a 'background of animosity' in the relationship and the couple had 'made threats and insulted each other via social media'.

Her older brother, Julius, 21, said Dada regularly threatened Katerina with violence if she went to police.

One time, Julius said he contacted police after Dada threatened to kill his girlfriend because he suspected she had been talking to other boys.

'She told me in [Romanian] not to saying anything because he had a machete in his trousers,' he recalled.

Julius said Dada was a psychopath whose controlling behaviour regularly led to violence, including when he threw his girlfriend out of his flat naked and forced her to get a taxi home.