A man has been found guilty of murdering a police custody sergeant with a gun he had smuggled into a cell. A jury at Northampton crown court convicted Louis De Zoysa, 25, of murdering Sgt Matt Ratana, 54, with a gunshot to the chest at a custody block in Croydon, south London, in September 2020. The court heard that De Zoysa, a former tax office data analyst from Banstead, Surrey, had managed to fire shots despite being handcuffed in a holding room after being found with bullets by members of a street patrol. After the initial shot, a further three shots were fired during a struggle with police officers. One hit Ratana in the leg and the final shot left De Zoysa with a “severe and life-threatening injury”. De Zoysa’s lawyers argued that he had not meant to shoot Ratana, and claimed he had a defence of diminished responsibility because he had had an “autistic meltdown”. But a doctor told the court that he did not think De Zoysa had been hyperventilating, based on video footage of the incident. The doctor also said De Zoysa “demonstrated a clear ability to control his actions”. The prosecutor, Duncan Penny KC, told the court De Zoysa had probably concealed the gun, an antique Colt revolver, under one of his armpits. The jury of seven men and five women unanimously decided, after five hours’ deliberation, that De Zoysa had deliberately pulled the trigger. De Zoysa nodded twice as the judge confirmed with him that he had heard the verdict being announced by the jury foreman. Ratana’s partner, Su Bushby, and Metropolitan Police commissioner Sir Mark Rowley were among those in the public gallery as the verdict was returned. Speaking afterwards Bushby said: “Whilst the court case has concluded, the constant feeling of grief and loss continues. My love for Matt, my gentle giant, will never end. He will never be forgotten.” After the verdict, trial judge Mr Justice Johnson thanked the jury for its deliberations on the case and said it had “fulfilled an onerous but critically important public duty”. Penny told the court that further firearms and ammunition charges faced by De Zoysa will be allowed to lie on the file at a sentencing hearing at the same court next month. The judge did not address any remarks directly to De Zoysa, who has communication difficulties due to brain damage from a self-inflicted gunshot wound, immediately before he remanded him in custody. Ratana, originally from New Zealand, had been a Metropolitan police officer for 29 years and was nearing retirement. The Independent Office for Police Conduct (IOPC) said on Friday it had recommended all forces carry handheld metal detectors in order to prevent a repeat of Ratana’s killing. The police watchdog added that the recommendation had been accepted and the National Police Chiefs’ Council was looking into implementing it. The scheme has already been implemented by the Met. Deputy assistant commissioner Stuart Cundy said the circumstances of Ratana’s death had been a “catalyst” for introducing new search measures. It has led to the issuing of over 4,000 hand held metal detectors to frontline officers, all frontline vehicles and all custody suites and the piloting of full body scanners in custody suites, Cundy said. Asked if the force had apologised to Ratana’s family Cundy said: “There’s only one person who killed Matt and that is Louis De Zoysa.” He commended the bravery of arresting officers, who did not find the hidden revolver during an initial search. They tried to disarm De Zoysa “without a second thought or care for their own individual safety” as he was firing the revolver in the custody suite, Cundy said. Asked how the arresting officers missed the gun during the initial search in the street, Cundy said they had “significant concerns” upon finding ammunition on De Zoysa’s person, re-cuffed his hands so that they were behind his back and took him to the police station to be searched in greater detail. It was not a “cursory search”, he insisted. “The officers themselves, they were concerned. Their evidence is that they did consider that Louis De Zoysa had access to a firearm. “At that point in time no one knew where it was, whether it was on him, whether it might be at his home address or some other location, which is why when De Zoysa was taken to the police station the first thing to occur was for De Zoysa to be searched.” An IOPC investigation has found there were no criminal, conduct or performance issues for the two officers, the Met said. Cundy said the “huge outpouring” of emotion and of people wanting to talk about the personal impact Ratana had had on them, showed what a “caring” individual he was. “It is clear he will leave that personal impact. He was a larger than life character in so many different ways. “As with all officers and staff who are killed, our memory for Matt will always stay alive.”