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Memorial stone unveiled in London for police officer shot dead
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Police to unveil memorial stone for hero officer Matt Ratana
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Matt Ratana: Memorial unveiled for officer killed in line of duty
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Memorials held for 'wonderful' police officer shot in Croydon
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Detectives quiz man over firearm used to kill sergeant Matiu Ratana
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CCTV captured fatal shooting of officer in Croydon custody suite
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