A man arrested on suspicion of supplying a firearm in connection with the murder of Sergeant Matt Ratana has been released on bail.
He has now been released on bail until late October, the Metropolitan Police said on Wednesday.
The man suspected of killing Mr Ratana, widely reported to be Louis De Zoysa, remains in a critical condition in hospital.
He was injured after allegedly opening fire in the custody suite as officers prepared to search him with a metal detector, police said.
Police investigating the murder of Sgt Ratana are meanwhile still carrying out searches at a house, believed to be the suspect’s family home, in Southbrook Road, Norbury, south-west London, and a property in Park Road, Banstead, in Surrey.
The Metropolitan Police said the second location includes access to several derelict buildings and more than 30 acres of land, with the “complex” search expected to take days to complete.
Croydon Custody Centre, where the shooting took place, remains a crime scene, while searches in London Road, in Pollards Hill, south London – where De Zoysa was arrested – and a location in central London have also been carried out.
Speaking on Tuesday, deputy assistant commissioner Stuart Cundy said: “It is five days since the murder of our colleague and our work continues at a high tempo.
“We have traced a number of witnesses who have been able to contribute significant information about the events leading up to the shooting.
“We continue to pursue multiple lines of inquiry and consider the results of initial forensic examinations, including of the gun recovered from custody.”
No police firearms were discharged in the incident, and the case is not being treated as terror-related.