Watch the video footage recorded by Banaz Mahmod

Banaz Mahmod repeatedly, over a period of two months, went to her local police station to report her increasing fears for her life.

She even handed an officer a list of names of young Kurdish men that she said had been ordered by her father and uncle to kill her.

A Scotland Yard investigation will now try to establish to what extent guidelines on handling “honour-based violence” were not followed.

The most glaring failure occured on New Year’s Eve in 2005, after Miss Mahmod managed to escape from a bungled murder attempt and ran into a restaurant in Wimbledon, southwest London. Drunk from the bottle of brandy that her father had forced her to drink – it was the Muslim woman’s first taste of alcohol – and covered with blood after smashing a window to escape, she desperately pleaded for help.

PC Angela Cornes, who responded to the 999 call, instead decided that the woman was a New Year’s Eve drunk who was attention-seeking and simply wanted her boyfriend. She also considered charging her with criminal damage for smashing the window, a consideration that was approved of during a call to her inspector. The police report failed to record Miss Mahmod’s claims that an attempt had been made on her life.

A businesswoman who comforted the petrified woman at the scene has told The Times that the officer was dismissive of the claims. “She was trying to get somebody to take her seriously, but nobody did,” Nurari Merry, 35, said. “The officers were slightly offhand with her. A male officer took notes and the female officer was a little bit dismissive of the situation. They asked her a couple of questions. But the ambulance crew took care of it and tried to work out what happened. The police acted as though she was just drunk or on drugs.”

PC Cornes also approached Miss Mahmod’s father to ask about her daughter’s allegations of attempted murder, a move that is forbidden in police guidelines because it alerts the family that the victim has approached officers.

The officer admitted in court that with hindsight she would have handled the situation differently.

Miss Mahmod was taken to hospital, where Rahmat Sulemani, her boyfriend, filmed her claims on his mobile phone. This film was pivotal in bringing her killers to justice.

The Times can reveal that 11 months before Miss Mahmod first went to Mitcham police, officers were issued guidelines on how to try to protect women who were deemed to have brought shame on their families. The standard operating procedures state that victims of “honour crimes” are, compared with most types of domestic violence, at “heightened risk” and should be treated “sensitively”. While it is recommended that the victim is put in contact with agencies that specialise in helping women at risk, Miss Mahmod received no such help.

It is not known whether PC Cornes checked to see if Miss Mahmod had approached police earlier, or whether other officers were aware that her sister had been taken into foster care, because of concerns for her safety, and as an adult had needed a police escort to collect her passport from the home.

Two men have fled to Iraq, where it is understood that they boasted openly of raping Miss Mahmod before garrotting her with a bootlace, cramming her body in a suitcase and burying it in Birmingham.

Commander Simon Bray, of the Metropolitan Police, admitted that officers should have given Miss Mahmod more advice about her plight. He added that the force would learn lessons from the “tragic case”. “Policing is full of ‘if onlys’,” he said. “Looking back we realise there are many things we could have done better. But if we are looking at individuals we have to ask whether what they did was reasonable at the time. Unless people are willing to give up their family and community connections it’s really difficult to provide them with the full level of protection we would like to give them.”

Hannana Siddiqui, of the Southall Black Sisters, an organisation that helps women at risk from “honour crimes”, said: “This case once again highlights the conspiratorial nature of ‘honour-based’ violence within minority communities, which puts women at extreme risk. We call on the Government and agencies such as the police and social services to take a robust approach in tackling violence against black and minority women to prevent future murders like that of Banaz.”

Darbaz Rasull, 24, from Hounslow, was cleared of perverting the course of justice.

After the case, Detective Inspector Caroline Goode, who led the murder inquiry, urged women who felt they were at risk from an honour crime to contact police. She said: “We are extremely pleased we have able to achieve justice for Banaz.

“Banaz was a loving and caring young woman who had the whole of her life in front of her and that life was brutally cut short by those who should have looked after her. In any terms, it was the ultimate betrayal.”

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