Suspects who fled the scene of an attempted armed robbery in which a teenager was shot in the back were caught with a 'bit of luck' in a routine traffic stop.
And police say the investigation into further suspects "could be reopened", as two men face lengthy spells in prison over the shooting.
Shortly before 2am on June 27 last year, a 19-year-old from London was shot after being attacked by a group of armed men who tried to rob him.
He had arrived nearby by taxi and made his way to the park off Adelaide Street when he was confronted by men wearing masks and wielding two knives and a shotgun.
"The likelihood is this was a planned attack on him in the hope of robbing him of drugs," prosecutor Ian James told Norwich Crown Court.
When the victim tried to flee he was shot at close range in the back.
In the early stages of the investigation police had "no idea" who was responsible.
But less than 24 hours later Kallum Eastall, 18, and Jake Brittain, 26, were arrested when they led police on a pursuit through Norwich.
The white Citroen they were driving, which belonged to Eastall's carer, had a marker placed on it as part of a missing person inquiry.
Officers discovered two knives, gloves and a balaclava made from knotted tights in the car and the pair were arrested.
On Tuesday Brittain and Eastall both admitted attempted robbery, having a firearm with intent to commit a robbery, and possession of two 15-inch knives.
Investigating officer, acting detective inspector Pete Wilson, said the arrests of Eastall and Brittain had been a "bit of luck".
"The morning of day one of the shooting we had no idea who it was," he said. "The victim was taken to hospital but he was quite well-sedated and had to have an operation."
A "large number of pellets" had to be pulled from the victim's bowel, lower back and backside, and he had to have a small section of damaged bowel removed.
"The following morning we became aware two people had been arrested in a small white Citroen," said A/DI Wilson. "We were by then aware from CCTV a small white hatchback was the vehicle used in the shooting and we decided to arrest them.
"It was a bit of luck but you never know when you stop a car what you are going to find."
The victim eventually identified Brittain as the shooter in an identity parade.
While shotgun residue was found on gloves and clothes found during searches of Brittain and Eastall's homes, an attempted murder prosecution against the pair was dropped.
Mr James accepted not guilty pleas on alternative charges of attempted murder and causing grievous bodily harm with intent on Tuesday.
"The issue might not be easy to solve as to who actually pulled the trigger in this case," he said.
"One has to consider whether it would be a good use of public time and money to pursue verdicts in relation to that count."
Police have not formally linked the incident with county lines drug dealing, despite Class A drugs being found in the victim's pocket and the fingerprints of a drug dealer being found on the weapon.
Two months after the shooting a double-barrelled shotgun was found in the loft of a home on Bertie Road.
On it were fingerprints of a county line drug dealer from Liverpool - James Elliott.
He has since admitted possession of a shotgun and dealing cocaine, and is awaiting sentence.
A/DI Wilson said the shooting was an "unprecedented" incident for Norwich.
"From their own admission they have gone to commit a robbery with a loaded firearm," he said. "They must have known something was likely to happen.
"It is almost unprecedented to have a random shooting on the streets of Norwich. It is not the first time a firearm has been discharged but the first time someone has been shot on the streets of Norwich.
"These things are extremely rare and we now know two people are going to be off the streets for a considerable amount of time."
He added it had been a "sophisticated" operation and new evidence only came to light as police listened in to Eastall's phone calls from custody.
Eastall and Brittain had both switched off their mobile phones in the hours leading up to the shooting, and while shotgun residue was found on their clothing nothing forensically linked them to the weapon.
But six live shotgun cartridges were recovered from the gutter of Eastall's home, wrapped in a sock, after he sent a coded message from custody.
Eastall had been referring to the shotgun as 'Johnny' and said: "Johnny's mates are in the gutter".
While the victim said he had been attacked by four men, police have spoken to two other suspects who had been in the park at the time.
One was discounted from the investigation as having nothing to do with the shooting.
Another was arrested but released without charge, but police say they may reopen the investigation.
"We are realistic and alive to the fact that someone who may have had knowledge of this and is involved has gone undetected," added A/DI Wilson. "If new evidence comes to light then that investigation against them can be reopened.
"If anyone has information about that third person we would be happy to listen."
Eastall and Brittain were remanded into custody and will be sentenced on September 9.
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