POLICE investigating the murder of Sergeant Matt Ratana are searching more than 30 acres of farmland in Surrey.

The 54-year-old, who lived in Goring, was shot dead by a handcuffed suspect, widely named as 23-year-old Louis De Zoysa, as he was booked in at a custody suite in Croydon, south London, in the early hours of Friday.

Detectives are yet to speak to the suspect, who remains in a critical condition in hospital after he shot himself as he opened fire with a revolver while handcuffed behind his back.

Deputy assistant commissioner Stuart Cundy said on Tuesday: “The murder of Sgt Ratana sent shockwaves through the Metropolitan Police Service.

“Nevertheless his colleagues are determined to find justice for him and his family.”

Searches are still being carried out 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.

Mr 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.

A man is still in custody at a south London police station after he was arrested in Norwich, Norfolk, on suspicion of supplying a firearm.

The suspect had been arrested for possession of ammunition and possession of class B drugs with intent to supply following a stop and search, before being handcuffed and taken to Croydon Custody Centre.

According to the Independent Office for Police Conduct (IOPC), he was taken into the building and sat in a holding area in the custody suite, then opened fire while still in the handcuffs as officers prepared to search him with a metal detector.

A fund in memory of Sgt Ratana has been set up by the Met’s Hayes Sports Club, known as the Warren, where Matt was said to be a regular visitor.

The New Zealand-born officer, who joined the Met in 1991, was head coach at East Grinstead Rugby Club.

Officers in his home country honoured Sgt Ratana with a haka as part of their Police Remembrance Day.

His partner of five years, Su Bushby, on Monday said: “I know Matt touched many, many people’s lives with his friendliness, patience, kindness, enthusiasm and caring ways.

“I had the pleasure of sharing five years of my life with this lovely man - my gentle giant, with his infectious smile and big heart. I think of him with tenderness and love.”