The wife of a wealthy Russian banker gunned down outside his executive flat has said that the shooting was an "act of pure unexpected violence".
Lorissa Gorbuntsov urged "any person, in this country or outside the UK" to come forward with information as she spoke of her heartache over her partner German remaining in a coma at a London hospital.
She said "this is a very emotional and complicated time" as Scotland Yard confirmed it was working with Russian police for the first time since the diplomatic fallout over the death of dissident Alexander Litvinenko.
Detectives leading the investigation also revealed that they had found a weapon, said by sources to be a pistol.
Mrs Gorbuntsov said: "This is a very emotional and complicated time for us. I would like to firstly thank everyone who is currently helping and supporting us, especially the Metropolitan Police. Their support has been of the highest standard.
"We as a family would like to appeal for any person, in this country or outside the UK, to come forward and provide the police with any information which will assist in the capture of the person or persons behind the attempted murder of my husband German.
"This is an act of pure unexpected violence, which should be treated as so. Please come forward so that justice can prevail."
The Metropolitan Police confirmed it was receiving help from Russian counterparts in the hunt for the suspected would-be assassin. Officers are still searching for a Hackney cab driver who dropped Mr Gorbunstov off shortly before he was gunned down.
Mr Gorbuntsov remains "critical but stable" under armed guard in hospital after the attack near Canary Wharf, east London.
Mr Gorbuntsov was shot a number of times as he entered his block of flats by a suspect described as white, 6ft and slim. He was wearing a dark hooded top and was seen running from Byng Street away from Westferry Road, towards Marsh Wall.
The Press Association, photo: Metropolitan Police