Two men arrested by detectives investigating the murder of Pc Sharon Beshenivsky in Bradford last month are being questioned in West Yorkshire.
Muzzaker Imtiaz Shah was one of two men arrested
Muzzaker Imtiaz Shah, 24, who had been named as a suspect, was one of the men held after an armed operation in Newport, south Wales, on Monday.
He and a 23-year-old were brought to West Yorkshire overnight, police said.
The search for another suspect, Mustaf Jama, 25, continues and will feature on Tuesday's Crimewatch programme on BBC1.
His brother, Yusuf Jama, 19, has already appeared in court charged with Pc Beshenivsky's murder.
West Yorkshire Police said the two men arrested in Wales were brought under tight security to a police station in the county late last night.
Cromwell Road in Newport was sealed off twice in 24 hours
They can be held for 24 hours before officers must apply to a superintendent for an extension.
The men were arrested after armed officers cordoned off Cromwell Road in the Maindee area of Newport for the second time in less than 24 hours.
The operation involved officers from Gwent, West Yorkshire and Metropolitan Police.
Police said there was "no indication" that Mustaf Jama was still in the area.
They are to appeal for information about his whereabouts on the BBC's Crimewatch programme on Tuesday.
Det Supt Andy Brennan, who is leading the investigation, reminded the public there is a £90,000 reward available for information leading to the arrest and conviction of those responsible for Pc Beshenivsky's death.
Pc Beshenivsky was shot dead while investigating a robbery at a travel agency in Bradford city centre on 18 November.
Her colleague, Pc Teresa Milburn, 37, was also shot and injured.