CCTV shows man believed to be suspect in killing of MP Sir David Amess

This CCTV footage is one of many pieces of evidence counter-terrorism officers are investigating in relation to Sir David Amess' death

CCTV footage taken from a shop close to the home of a man suspect of killing Sir David Amess MP is being studied by police.

In the video, taken at 8.44am on Friday morning - the day the MP died after the fatal stabbing at a surgery to meet his constituents - a man can be seen strolling down the pavement.

The man in the footage is wearing a long green coat and trainers and holding a rucksack. He disappears in the direction of a London Underground station around the corner.

Three hours later and 40 miles away, Sir David was killed.

And one of many questions for the police is whether the man in the video is the suspect.

ITV News Global Security Editor Rohit Kachroo explains how CCTV footage taken from a shop is linked to the police investigation into Sir David's death

Ali Harbi Ali, a 25-year-old British citizen, was arrested after the Southend West MP was stabbed at a surgery to meet his constituents on Friday.

Ali is spending a fourth night in police custody. Detectives have until Friday to question him in custody after they were granted a warrant of further detention.

Police think they know the motive behind the killing and believe the attack to be an act of terrorism.

But they’re still trying to work out precisely why it happened, and why this MP was targeted.

This video has been seized, this extract studied, one of many pieces of evidence for the counter terrorism officers investigating what happened last Friday and what led up to it.

Three properties were seen being searched by police between Saturday night and Sunday morning.

ITV News Global Security Editor Rohit Kachroo talks through Ali Harbi Ali's family background. Ali's relatives have served as top advisors and diplomats:

In a statement on Sunday, Scotland Yard said: “Late on Friday, whilst in police custody, the man was subsequently further detained under section 41 of the Terrorism Act 2000 and he is now being held at a London police station.

“On Saturday, detectives were granted a warrant of further detention at Westminster Magistrates’ Court, allowing them to keep the man in custody until October 22, when the warrant expires.

“As part of the fast-paced investigation, officers have attended three addresses in the London area and conducted searches.

"One of these searches has concluded and the others are ongoing. A post-mortem examination has taken place today.”

On Monday, MPs in the House of Commons came together to pay tribute to Sir David.

After hours of tributes, MPs were led by Speaker Sir Lindsay Doyle to St Margaret's Church for a prayer and remembrance service.

Watch the remembrance service here: