The most prolific weapon ever traced by police in the UK has now been taken off the streets. Here is the story of how police ended its reign of terror.
It is a story of organised crime, drug dealers and petty disputes – but also one of police intelligence and sophisticated ballistics forensics.
After 19 shootings in just seven years, the gun, known to police as "Link Series 4", is now safely off the streets.
The weapon is a Beretta 9000 pistol – small, compact and heavier than you might think.
It is a self-loading pistol, chambered for 9mm parabellum and designed to be a lethal firearm.
It's not known how it first came to the UK. According to the National Crime Agency, handguns are often smuggled in from abroad, sometimes via ferry ports or hidden in parcels.
What we do know is that it was first used on the outskirts of Glasgow in the early months of 2010.
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Its first two discharges happened in the space of a week, the first causing damage to a sign post in Erskine and the second, at no obvious target in Port Glasgow.
"We think it's likely the gun was being test fired," said DCI Steve Reardon of Merseyside Police, whose team eventually traced Link Series 4.
"The second discharge caused no damage, there were only cartridges collected at the scene."
Whoever was testing the weapon then either moved South or passed it to someone else in the Liverpool area. It was here that its use became increasingly prolific and violent.
Between 2010 and 2014 it was used in 16 shootings, predominantly in the Kirkby, West Derby and Anfield areas.
These incidents often involved "warning" shots fired at homes or cars.
In some episodes individuals were specifically targeted, sought out and attacked. In four cases people were injured. Police said a number of the victims were lucky to be alive.
A great frustration to police at this time was that none of the victims would cooperate with them.
"They were tit-for-tat shootings," says DCI Reardon. "I will leave it to the public to decide why someone shot seven times, who was lucky to survive, wouldn't cooperate with us.
"These people are not the old organised crime groups with loyalty and pride in what they do. These are young, chaotic people who will use firearms to solve petty disputes usually to do with drugs.
"We knew if we targeted the gun we'd get the people."
And target the gun was exactly what police were doing.
In an plain building in an unassuming Birmingham suburb, staff at the National Ballistics Intelligence Service (NABIS) were using forensics to link the shootings to one gun.
Every individual weapon leaves unique markings on the ammunition it fires. As long as bullets or cartridge cases can be recovered from the scene of a shooting, NABIS can analyse the markings and work out if they've seen that gun before.
It means they can trace how weapons are being moved around and build a profile of the type of incidents they are involved in. The aim, of course, is to close in on who might be using them.
"I'll put two cartridge cases under two microscopes, one on the right and one on the left," explains Martin Parker, chief scientist as NABIS.
"Then, looking at the images on a split screen, I'm comparing the fine detail of these markings, like a supermarket bar code or fingerprint."
A state-of-the-art database allowed Martin and his team to compare thousands of samples in just a matter of minutes, invaluable when you have 19 incidents to link.
"Manual searching might have picked up a number of links, but for older shootings, the only way you're going to get that sort of link is with automation."
Back in Liverpool, police had a suspect in relation to the 17th time the gun was used, a shooting at the Moorfield Shopping Centre in Kirkby that left the victim seriously injured.
They arrested a local man named Adam Bigley. There wasn't enough evidence to charge him and he was released, but he would remain a key character in the search for the Link Series 4.
The 18th shooting came a year later. The gun was fired 10 times at a property in Wavertree. Although no suspect was identified, the geography was significant.
The shootings immediately preceding this had all been in Kirkby, police believed it was likely they had been carried out by an organised crime group there. But now the gun had moved to a different "patch", indications were it may have changed hands.