A firearms officer has told an inquest that he "could not justify" shooting barrister Mark Saunders as he drunkenly waved a shotgun in the air.
The officer, known only as Alpha Zulu 14 (AZ14), said the 32-year-old did not appear to aim the 12-bore weapon at police surrounding his home in Markham Square, Chelsea.
He told Westminster Coroner's Court that he could not see if the gunman had his finger on the trigger in the seconds before he was fatally wounded in a volley of police shots.
The court heard the breach of Mr Saunders's shotgun was found in an "open" position, suggesting it could not have been fired, when officers stormed his home.
AZ14, a member of Scotland Yard's diplomatic protection group, was one of the first armed officers to arrive after Mr Saunders blasted his shotgun on May 6, 2008.
Giving evidence, the officer said he was in the basement of 1 Bywater Street when the fatal shots were fired at 9.32pm, but did not pull the trigger himself.
He said: "If I did not believe the firearm was pointing at anybody I was not going to pull the trigger.
"I have to believe there is a threat to life. That threat to life is going to come when I believe the firearm is pointing at somebody. Until that happens I am not justified in my actions to pull the trigger."
In a statement written after the shooting, AZ14, who was armed with an MP5 carbine, said he could not be "certain" anyone was in the line of fire.
He said: "I could also not see his hand in relation to the trigger. At this moment I could not justify taking a shot."
