LONDON (Reuters) - The widow of a senior MQM politician murdered in London last week made a highly emotional appeal for help in catching his killers on Thursday as police said they were still investigating the reason for the attack. Imran Farooq, 50, a founding member of the Muttahida Qaumi Movement, was found dead outside his home in the Edgware area of north London last Thursday evening. He had been repeatedly stabbed and had suffered head injuries as he returned home from work. His death led to a shutdown of Karachi, after the MQM declared 10 days of mourning. Someone, somewhere knows something about my husbands murder, his wife Shumaila Imran, 42, told reporters, choking back tears. His murder a week ago has devastated me and left our family in a state of shock and disbelief, she added, before being led, weeping, from the room by a family friend. Farooq, inactive in politics for about two years, claimed asylum in Britain 11 years ago after more than seven years on the run from Pakistani police who accused him of involvement in murder and other serious crimes. He denied the charges. His killing is being investigated by London polices Counter Terrorism Command. However, a police spokeswoman said this was because of Farooqs political profile rather than because detectives believed the murder was a political assassination. She declined to say whether anything had been stolen from Farooq. Detectives investigating the attack are keeping an open mind as to the motive behind this attack, said Detective Chief Superintendent Neil Basu. I would like to reassure everyone that detectives are doing all they possibly can to catch those responsible. The murder shocked local Pakistani and Muslim communities, he added. Farooq was one of several senior members of the MQM who have taken refuge in London. The partys top leader, Altaf Hussain, has lived in self-exile in the British capital since 1992.