The statement said Dr Farooq’s murder would have required careful planning and help from other people, some of whom may have provided assistance or information unwittingly.

“Dr Farooq was on his way home from work when he was attacked outside his home in Green Lane, Edgware, London, shortly before 17:30hrs on Thursday ,16 September 2010.

The 50-year-old died as a result of multiple stab wounds and blunt trauma to the head. A five-and-a-half inch bladed kitchen knife and a house brick used in the attack were recovered at the scene.”

The Met Police said “To date they have spoken to 4,555 people, reviewed 7,697 documents, followed up 2,423 lines of inquiry and seized 4,325 exhibits.

It is thought Officers have been in regular contact with the Pakistani authorities to gather evidence that could assist in bringing to justice the killers of Dr Imran Farooq. They have named two men as wanted in connection with the murder:

Moshin Ali Syed, 30, a Pakistani national who was in the UK between February 2010 and 16 September 2010; while another man 36-year-old Muhammad Kashif Khan Kamran, a Pakistani national who was in the UK between early September 2010 and 16 September 2010.

Met police said anyone who could assist should call the police incident room on +44 (0)20 7230 2717 or contact the police by email at SO15Mailbox-.DrFarooqMurder@met.police.uk

“We understand that people may have concerns about speaking to the police and would like to offer reassurance that information will be dealt with sensitively.”

Three men previously arrested in connection with this investigation have all been released without charge:

A 39-year-old man arrested on 9 December 2010, at an address in Camden on suspicion of murder, and also on suspicion of robbery in October 2009. He was subsequently released without charge in March 2012. Similarly, a 54-year-old man arrested on 24 June, 2013 at Heathrow airport on suspicion of conspiracy to murder. He was subsequently released without charge in October 2014.

While the third person, a 31-year-old arrested on 27 August, 2014 at an address in Waltham Forest in connection with the murder. He was subsequently released without charge in May 2015.

“Imran Farooq’ s son misses his dad'”

The son of slain MQM leader, Alishaan Farooq, posted his pictures with his father Imran Farooq, with a caption “I miss you daddy.”

In another set of pictures, he captioned it “my dad is the best”