An investigation into the stabbing of a father, who was murdered months later, is to be examined by the Independent Police Complaints Commission (IPCC).
Flowers have been left outside the Woodhams' house
Police have apologised to the family of Peter Woodhams, 22, who was shot after challenging youths outside shops in Canning Town, east London, on Monday.
On 21 January he was stabbed in the neck near the same parade of shops.
The Metropolitan Police Authority has asked Met Commissioner Sir Ian Blair for a report into the response.
Mr Woodhams's fiancee, Jane Bowden, said she phoned police repeatedly for five weeks but detectives never took a statement from her. No-one has been charged over the stabbing.
On Monday night, Mr Woodhams, a television satellite engineer, had returned home in his car complaining of "trouble outside".
He then went outside on foot, apparently to challenge the gang, and was shot nearby in Leslie Road. He staggered back to the house and collapsed in front of his fiancee.
Colleen Bowden told the BBC her sister had been left distraught and the couple's three-year-old son kept asking when his daddy was coming back.
Local councillor Paul Schafer said residents felt "horrified, absolutely horrified... and let down".
Metropolitan Police Commander Rod Jarman said: "We will robustly deal with any failings in our investigation of the previous incident and make sure that those matters are dealt with.
"I would also like to make my apologies for any hurt that that investigation may have caused the family."
Announcing the investigation into the force's handling of the stabbing, David Petch, IPCC Commissioner, said the family have not made a formal complaint, but they will offer to meet them.
He also stressed they are not looking into the current murder investigation.
"There has been considerable public concern about this case and I therefore decided our own investigators should look at the police's response to the stabbing incident in January," he added.
"It is vital that Mr Woodham's family, the police involved, and the public at large can have confidence that their concerns about the initial incident will be robustly investigated."
Jim Fitzpatrick, Labour MP for Poplar and Canning Town, said: "When there is a violent attack, such as has been reported on Mr Woodhams in January, one would have hoped that steps would have been taken to make sure there wasn't a repetition."
Detectives are going through CCTV footage from Freemasons Road on Monday night and are trying to trace anyone who saw Mr Woodhams near the shops, or saw the shooting.
A 14-year-old boy has been questioned and released on bail.