A gun has been recovered and forensically examined by UK Metropolitan Police as the murder investigation continues into the death of New Zealand-born cop Sergeant Matt Ratana.
"Almost forty-eight hours into the investigation, we are pursuing various lines of inquiry and recovering evidence from the four crime scenes," Deputy Assistant Commissioner Stuart Cundy, head of the investigation, said.
Rigorous forensic searches are being carried out at the crime scenes, including the police custody centre where the alleged shooting took place.
The other three locations are in the surrounding area and in Surrey, South East England.
Police are also examining and reviewing CCTV and bodycam footage from police officers.
"Our murder investigation will seek to establish why Matt was shot. One of my priorities is to ensure any future criminal prosecution is not jeopardised.
"I know this is important to the public too and I’d ask for everyone not to speculate," the deputy assistant commissioner added.
A 23-year-old suspect remains in critical condition and due to his state police have yet to speak with him.