The man suspected of shooting dead Sergeant Matt Ratana in a south London custody suite is 23-year-old Louis De Zoysa, Sky News has confirmed.
The suspect, who remains in hospital in a critical condition and has therefore not been spoken to by detectives, is from Norbury, south London.
Sgt Ratana, 54, was allegedly attacked by the handcuffed man who was handcuffed and who investigators say then shot himself. No police weapons were shot and the case is not being treated as terror-related.
Another man has been arrested on suspicion of supplying a firearm following the killing of Sgt Ratana, who died in hospital after the alleged south London attack in the early hours of Friday.
Ratana was originally from Hawke's Bay on New Zealand's North Island but had served with the Metropolitan Police for much of his career.
He is the eighth officer in the UK to be shot dead in the last 20 years.
Friends and teammates of the officer, who was a popular head coach at East Grinstead Rugby Club, gathered in tribute to the "irreplacable" and "incredibly generous" man.
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His cousin Adrian Rurawhe described him as an "awesome person" who "loved being a police officer".
Boris Johnson also paid tribute to officers who had died in the line of duty and who "represent the very best of us".