A man has been arrested on suspicion of supplying a firearm following the fatal shooting of a police officer in a custody suite.
The arrest took place in Norwich around 2am on Sunday and the suspect is currently being detained at a south London police station.
Meanwhile, the suspect for the shooting remains in a critical condition in hospital and officers investigating the murder say they have not yet been able to speak to him.
Sgt Ratana, 54, was allegedly attacked by a man who had been handcuffed who investigators say then shot himself.
Friends and teammates of the officer, who was a popular head coach at East Grinstead Rugby Club, have gathered in tribute to him.
There were two periods of silence – for junior and senior members – and the club flag was flown alongside the New Zealand flag and the All Blacks rugby team flag to honour Sgt Ratana's roots.
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Ryan Morlen, the club's assistant head coach, said the news of his death would "take time to process".
He said: "It's tough really with the loss of Matt, he's an irreplaceable figure. The club here, from juniors, seniors, to the women's team they're going to really miss Matt.
"As a community he brought a lot of things together. I spoke to Matt every single day… and there are thousands of people out there that really looked up to him."