The Swedish hitman hired to murder drugs gang kingpin Flamur Beqiri mistakenly left a plane ticket with his name on it that was found by detectives following the shooting.
Anis Hemissi, 24, killed the dad in front of his family in Battersea on Christmas Eve.
The gunman wore latex masks and disguises including a litter picker’s outfit for reconnaissance, before carrying out the shooting on December 24, 2019.
Hemissi took steps to cover his tracks, aided by a clean-up team tasked with secretly tidying up all traces of the crime on Battersea Church Road.
But they all missed the ripped-up plane ticket with part of Hemissi's name visible on it.Scotland Yard detectives say the crew appeared to have 'underestimated' just how extensive London CCTV's network coverage is.
A series of mistakes, including a 'ladies' bike' used as a getaway ride, allowed them to trace Beqiri's killer's movements and lead them to crucial pieces of evidence to net their man.
A rapid trawl of CCTV over the days following the killing allowed detectives to trace the shooter on foot.
They were then able to trace his bicycle journey from Battersea Church Road down the Thames path to a flat in Oyster Wharf, using the footage.
A local team, hired to clean up, had removed a large suitcase and a rucksack on Christmas Day.
But they would arrive to find police already inside when they returned two days later to finish the job.
Metropolitan Police Detective Sergeant Brett Skowron said: “The defendants have underestimated quite how much CCTV there is throughout London.
“We think they would never have thought that we would actually have been able to track them as far back to that flat in the first place.
“That’s because in Sweden they have much less CCTV due to the restrictions of what it can be used for.”
The flat was a treasure trove for forensics investigators, who recovered gunshot residue from the Ridgeback bike used by Hemissi in his getaway.
Officers also found the litter picker and black bin bags used as part of Hemissi’s disguise.
DNA and fingerprints from Hemissi as well as Estevan Pino-Munizaga, 35, the man who had rented the flat, were also found on items such as drinks containers, food and rubbish.
Crucially for the investigation, in one of the bins was a ripped up piece of ticket stub with part of Hemissi’s name on it.
Officers were able to track the killer to Heathrow, from where he flew to Copenhagen, Denmark, in the early hours of Christmas Day using his own name.
Bank records obtained by Swedish police showed the gunman had bought a high-vis jacket and trousers, boots and a black beanie hat he used along with a latex mask and litter picker to pose as a street cleaner.
Senior Crown Prosecution Service prosecutor Louise Attrill said the shooting was “a professional organised killing - but there were mistakes.”
One of the errors was made by Pino-Munizaga when he bought a distinctive dark green “ladies’ design bicycle”, with a basket on the front, to be used by the gunman in reconnaissance.
Mr Skowron said the bike would “stand out when you see a male riding it” but was the common “stepover” design ridden by men and women in Sweden.
Hemissi stopped using the bike, along with his hi-vis litter-picker’s disguise, after he was confronted by a Battersea resident who found it suspicious that he was cleaning both a private estate and a council road.
Dog walker Jeremy Lyons asked the hitman: “Excuse me, who do you work for? Who do you work for?”
Hemissi walked off as he was told: “Get away from this estate please.”
Who was Flamur Beqiri?
Beqiri, 36, was a kingpin in an international drugs gang.
He was the brother of Real Housewives of Cheshire reality TV star, Misse Beqiri.
The father-of-one was shot dead on his doorstep in front of his wife and two-year-old son.
His killer's trial heard how he was targeted as part of a feud with a rival organised crime group headed by Amir Mekky, 24.
The gunman, Hemissi, was a professional kickboxer and hitman.
He was found guilty of murder and possession of a firearm at Southwark Crown Court on Friday after a two-month trial.
Fellow Swedish national Estevan Pino-Munizaga, 35, was acquitted of murder but found guilty of an alternative charge of manslaughter.
Tobias Andersson, 32, and Bawer Karaer, 23, also from Sweden, were acquitted of both charges.
Clifford Rollox, 31, from Islington, north London, and Dutch national Claude Isaac Castor, 31, from Sint Maarten in the Caribbean, were found guilty of perverting the course of justice after being hired locally to clean up the flat where the killers had stayedMrs Justice Cheema-Grubb said she will sentence those found guilty next Friday 18 February.