The Independent Police Complaints Commission (IPCC) criticised failings in the handling of Banaz Mahmod's complaints against her family.
She asked police for help four times, even giving officers a list of men she thought would harm her, but was not taken seriously.
Miss Mahmod, 20, disappeared from her home in Mitcham, south London, in January 2006, and her body was found buried in a suitcase in a garden in Birmingham three months later.
Following an Old Bailey trial her father and uncle were jailed last July for her "barbaric" murder.
The IPCC today released the results of its investigation into how Metropolitan Police and West Midlands Police officers dealt with her complaints before her death.
The police watchdog concluded that three matters were handled "appropriately" and with compassion, but noted delays, insensitivity and a lack of understanding in another two cases.
Two Metropolitan Police officers - a constable and an inspector - will now face an internal disciplinary panel to explain their actions over an incident on New Year's Eve 2005 when her family first tried to kill her.
On that day Miss Mahmod's father lured her to her grandmother's house and forced her to gulp down brandy.
In terror she escaped by smashing a window and fled to a cafe in Wimbledon, south-west London.
But the officer who interviewed her about what had happened, Pc Angela Cornes, dismissed her account as fantasy, the Old Bailey trial heard.
Pc Cornes was more concerned that Miss Mahmod had broken a window as she escaped and wanted to charge her with criminal damage.
No date has been fixed for the disciplinary panel and both the IPCC and Scotland Yard refused to confirm the names of the two officers involved.
The IPCC also raised concerns about the handling of complaints of historic physical and sexual abuse made by Miss Mahmod to the Metropolitan Police on September 14, 2005.
The case was passed to West Midlands Police because the alleged incidents took place there, but she was only interviewed on October 10 and did not sign her statement until January 10, 2006.
The police watchdog ruled that the Met could have done more in its dealings with Miss Mahmod, lines of inquiry were not followed and there was poor supervision.
It also found that the initial West Midlands Police investigation was "flawed, not done in a timely fashion and poorly supervised".
The IPCC recommended that four Met and three West Midlands detectives should receive written warnings over this matter.
Another Met constable should receive words of advice and a West Midlands officer should receive training over his failure to provide adequate supervision, it said.
IPCC Commissioner Nicola Williams said: "Banaz Mahmod was a young woman who lost her life in terrible circumstances.
"Her murder has been termed an 'honour killing' and there has been much debate about this subject, which I do not intend to add to.
"The IPCC's investigation focused on how two police forces dealt with allegations and whether more could have been done to assist a woman who was living in fear.
"It is clear that the police response was at best mixed. In relation to three of the incidents we investigated, we found the police force involved, the Metropolitan Police Service, had dealt with matters appropriately and sensitively.
"However, in relation to two incidents we have found that Banaz Mahmod was let down by the service she received.
"There were delays in investigations, poor supervision, a lack of understanding and insensitivity."
The IPCC also made recommendations aimed at improving policing practice, including the review of procedures relating to the investigation of sexual offences.
Scotland Yard said in a statement: "The MPS has been informed about the findings of the IPCC investigation into how it handled complaints from Banaz Mahmod prior to her murder...
"We do not think it is appropriate to comment further at this stage until all disciplinary proceedings are complete."
:: Two men are due to stand trial at the Old Bailey in July in connection with Miss Mahmod's killing.
Amir Abbas, 30, of no fixed address, is charged with conspiracy to murder and perverting the course of justice.
Dashti Babaker, 21, of Redcar Street, Camberwell, south-east London, is accused of perverting the course of justice.
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