A text message sent to Arsema Dawit days before the teenager was stabbed to death warned her: “If you don’t want me any more then no one can have you.”

Minutes after she died, a message was sent to a supposed rival for her-affection, saying: “You have taken the love of my heart. I hope you are happy now she is dead.”

The disclosure comes as police charged Thomas Nugusse, a 21-year-old student originally from Eritrea and now living in Ilford, Essex, with her murder. He is due to appear at Greenwich Magistrates’ Court today.

It is believed that the killer lay in wait for Arsema on Monday as she came home from school. She was stabbed at least ten times in a lift in the block of flats where she lived in Waterloo, Central London.

It has also emerged that two days before her death Arsema was stalked as she celebrated her 15th birthday. She was contacted by a man who said that he could hear music from her fourth-floor flat.

Arsema and her family had complained to police in April after a man assaulted her but it took officers 12 days to interview her. A police internal investigation has been started.

A man was finally arrested at near-by Hungerford Bridge, where he was said to be threatening to kill himself. Police sources say that he has no criminal record or any history of mental illness that they can find.

Farah Carver, 43, a close friend and neighbour of the family, said that Arsema received a number of text messages threatening to kill her.

“She received many texts in the weeks before her death, some threatening to kill her and others declaring their love,” she said. “At 3.50pm, just five minutes after she had been murdered, the killer sent a text to someone he believed was a rival in love for Arsema, blaming him for her murder.

“The police have taken away these phone messages. But the family believe it is too little, too late.”

She said that Arsema’s family dispute a statement put out by the police saying that they had tried to interview the teenager last month about an alleged assault by the man. “They cannot believe that the police had contacted Arsema at school for an interview, and yet they were never informed by detectives or the girl,” she said.

Arsema’s mother, Tsehainesh Medhani, came to Britain in 2003 from Eritrea and claimed asylum. Her three children followed soon after. Their father remains in Eritrea.

The Independent Police Complaints Commission said that it would investigate police handling of complaints from the family of the youngster.

Arsema’s family had told police on April 30 that she had been assaulted by an obsessive man who had threatened to kill her at a McDonald’s restaurant near where she lived on April 16. But officers did not speak to Arsema until May 12, when a Safer Schools officer visited her at her school, Harris Academy. She denied any knowledge of the incident.

Officers had continued with the investigation and rung her mother on May 19 and again, it is believed, on the morning that her daughter was killed.

Scotland Yard has announced that the investigation and relevant procedures will be reviewed separately by the Violent Crime Directorate and the Directorate of Professional Standards to see who did what and when.

They will want to know what officers were doing in the 12 days before Arsema was finally spoken to.

It is believed that although Arsema and her mother gave police a name of a suspect it was not 100 per cent correct. The suspect is thought to have met Arsema at St Michael’s Community Church, where she was an enthusiastic member of the Eritrean church and sang in its choir.

A worker at the McDonald’s in Walworth Road, where Arsema was allegedly assaulted, told The Times that police had not been there to see if there was any closed-circuit television footage featuring Arsema and any suspect. A spokesman said that the company was helping police with their inquiries but refused to say when it began doing so.

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