Arsema Dawit's body was found in a lift
Independent police investigators are to look at how officers handled an allegation of assault made by the family of a girl who was later killed.
Arsema Dawit, 15, died five weeks after her family made a the complaint to the Metropolitan Police (Met).
The Met has launched its own internal inquiry into Arsema's death on 4 June in Waterloo, south London.
She was stabbed in the lift of Matheson Lang House, Baylis Road, where she lived.
She is believed to have just returned from school when she was attacked.
Relatives had complained to police on 30 April that the teenager had been stalked and attacked by a man who threatened to kill her.
In a statement Arsema's mother Tsehainesh Medhani said: "When my daughter was threatened, I went to the police seeking protection - sadly, this did not happen.
"I have lost a precious, beautiful and much-loved daughter who was kind, generous and loving.
"I feel as though a light has gone out of my life."
The IPCC (Independent Police Investigation Commission) said: "Our investigation will examine the circumstances surrounding the police contact with Arsema between 30 April and 2 June 2008.
"In particular we will look at how the police responded to an initial report made by Arsema at Kennington police station on 30 April of assault and threats to kill, and the subsequent investigation by officers from a neighbouring borough.
"We are very aware of public concerns about the police response to reports of threats of violence, which we have investigated in previous cases.
"Our investigation will also examine whether there are further lessons for the police service, including whether any changes in police policy or practice would help prevent a recurrence of this type of tragedy.
"It is vital that Arsema's family, the police involved, and the public at large can have confidence that the concerns expressed will be robustly and fairly investigated."
On Wednesday the Metropolitan Police said it has referred the case to the IPCC.
It added: "As would be expected in circumstances such as these, we have commissioned an internal review of our investigation into the crime allegation made by Arsema Dawit and her family on 30 April this year."
Thomas Nugusse, 21, of Ilford, east London, has been remanded in custody by magistrates charged with Arsema's murder.