Police investigating a drive-by shooting have urged people not to post any “harrowing” footage online.
John Pordage, 34, was shot in the chest outside a filling station in Chelmsford by someone in a car in the early hours of Saturday.
Essex Police said people with mobile phone or dashcam footage should contact the force.
A former colleague has paid tribute to Mr Pordage, saying it was a “pleasure to have known him”.
Police said they believed Mr Pordage, who lived in Galleywood, Essex, knew his killer and was targeted.
“If anyone does have any… footage that has captured any part of the incident, before during or after… we’d obviously ask for that to be sent to us,” said Ch Insp Ronnie Egan.
“Please don’t share it publically because it is obviously harrowing and will form part of our investigation.”
The shooting took place at the BP garage on Baddow Road, near the Army and Navy roundabout, in the town at 02:10 BST.
A friend and former colleague of Mr Pordage said the keen bodybuilder, who worked as an electrician for a fire alarm company, was “really well-known and popular” in Chelmsford.
Josh Grimble, 23, who is from the town, said: “He was called Big John for obvious reasons… He loved his gym and cross-fit.
“I drove past him a few days ago and stopped for a quick chat, not knowing that it would be for the last time.
“It was a pleasure to have worked with him and known him.”
Mr Grimble said Mr Pordage had competed in a number of Strong Man competitions.
More friends have also paid tribute online, describing him as a “big friendly giant” and one of the “nicest men”.
Mr Pordage was standing with a 25-year-old man, who was unhurt, when they were shot at from someone in a blue Ford Fiesta which then drove off.
The road outside the petrol station remains closed on Sunday while forensic officers continue their investigation.