Horror of gun attack

These are the terrifying moments when a businessman was gunned down outside his home in a suspected assassination attempt.

The dramatic CCTV images show the gunman approaching Mr Butler and then chasing him around a car. Seconds later, the businessman stumbles and is shot at close range.

Detectives released the pictures today in the hope that someone will recognise the gunman, who made little effort to disguise his identity.

Police have arrested a Scotland Yard detective and a private investigator on suspicion of conspiracy to murder. Mr Butler, who is married, has not recovered consciousness. Doctors say any attempt to remove a bullet lodged against his spine would kill him.

He was involved in a security business and ran a security clamping firm for the council but sources say he is also well known to police.

The pictures of the shooting were caught on a CCTV camera outside his home in Green Lane, Dagenham.

Mr Butler had got out of his burgundy P-reg Land Rover before midnight on 13 October when the gunman walked up, chased him into the main road, shot him at least once and ran off. Police believe he escaped in a red Japanese hatchback. Bleeding, Mr Butler struggled to the Matapan pub opposite his house, where the alarm was raised.

Detective Chief Inspector Dave Brown, leading the investigation, said: "Someone must have seen the gunman either waiting in a vehicle nearby or loitering.

"We are certain someone will recognise the gunman and it is essential he is apprehended as soon as possible. This was not a random attack. We believe the victim was targeted because of his business interests." He also appealed for the driver of a white car seen pulling onto Mr Butler's drive an hour before the shooting to come forward.

The detective arrested two weeks after the shooting and questioned about an alleged plot to kill Mr Butler was from a homicide investigation unit but not on the team investigating the attempted murder. The detective constable, 47, was held at his home in Hornchurch, Essex, and bailed pending further inquiries. He has been suspended.

A 41-year-old private investigator from Borehamwood was also held and bailed.

Anyone with information should call 020 8345 4362 or Crimestoppers anonymously on 0800 555 111.