Police are appealing to find a woman who comforted a teenage girl at a bus stop who had been raped while leaving a block of flats in north London.
The attack is said to have taken place just prior to 9pm on 6 March, as the girl in her mid-teens left the apartment block in Joyce Avenue, Edmonton.
The force is now seeking to find a witness, who it said may be able to assist with information about the crime.
After the assault, the girl went to Fore Street, where the police were called. While she waited at a bus stop for officers to arrive, a woman who identified herself as Sandra spoke to her and comforted her, Scotland Yard said.
However, upon the arrival of police, this woman left the area on a 149 bus heading towards London Bridge, and officers have since been unable to trace her.
She is a Black woman of medium build, and was wearing a black coat, long red skirt or dress, carrying a plastic bag, the force said.
Detective Constable Rebecca Mussington, from the local policing team in Enfield, said: “This woman spoke to and comforted the young girl and we really need to speak to her.
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“She may not realise it, but her evidence could be crucial. This is a very serious allegation of sexual crime against a young girl and I would appeal to this lady, or anyone else who has any information to come forward and tell us what you know.
“You can always call Crimestoppers if you do not want to give your name, but however you want to do it, please call.”
Any witnesses or anyone with any information is asked to call police on 101 quoting CAD6590/06Mar. To give information anonymously contact the independent charity Crimestoppers on 0800 555 111.