The man suspected of shooting dead police sergeant Matt Ratana has been named as 23-year-old Louis De Zoysa.
He was identified in news reports as he remained in hospital in a critical condition following the officer’s death at Croydon police station, south London, on Friday.
Mr De Zoysa was described as a reclusive young man who suffers from autism and lives with his parents a few miles away in Norbury.
The Metropolitan Police refused to comment on the name of the suspect but said that officers continued to "work around the clock" on the "detailed and thorough investigation".
However detectives have not yet been able to speak to him about the shooting.
Searches are still taking place at addresses on Southbrook Road, Norbury, and Park Road, Banstead, Surrey, as well as fthe custody suite where the incident took place at around 2.15am.
Sgt Ratana, 54, was shot as he dealt with a suspect who had been detained on suspicion possession of ammunition and possession of class B drugs.
The Independent Office for Police Conduct (IOPC) said the suspect opened fire while still in handcuffs as officers prepared to search him with a metal detector.
The suspect was also shot during the incident but police firearms were discharged, according to the Metropolitan Police.
On Sunday morning police arrested a second man in Norwich, Norfolk, on suspicion of supplying a firearm.
Hours later Met Commissioner Dame Cressida Dick paid tribute to Sgt Ratana at a morning wreath-laying at the National Police Memorial in central London to mark National Police Memorial Day (NPMD).
She said: "If some good can come out of this terrible incident in which we have had one of our officers murdered, it would be that more people can understand a little bit about the challenges of police work and to see us police as who we are - human beings, going to work to help people, to support people and to protect people. Matt was the epitome of that."
The Prince of Wales also provided a video message for a virtual service, saying: "The dreadful incident in Croydon on Friday is the latest heartbreaking evidence of the risks faced by our officers daily."
Sgt Ratana, was originally from New Zealand and joined the Met in 1991. He leaves behind a partner and a grown-up son.
In East Grinstead, the club flag was flown alongside the New Zealand flag and an All Blacks rugby team flag to honour Sgt Ratana's roots.
Tributes were laid outside the clubhouse and two periods of silence - for junior and senior club members - were held in memory of a man described by assistant head coach Ryan Morlen as an "irreplaceable figure".
Sgt Ratana is the first police officer to be killed by a firearm in the line of duty since PCs Fiona Bone, 32, and Nicola Hughes, 23, in September 2012.
Additional reporting by Press Association