Five men have been arrested and a major search operation is under way across Northern Ireland over the murder of police officer Ronan Kerr.
The 25-year-old Catholic policeman was killed when a bomb exploded under his car in Omagh on 2 April.
About 200 officers are currently involved in seven searches in Coalisland, Toomebridge, Bellaghy and Ballyronan.
The five men, aged from 22 to 46, were arrested under the Terrorism Act.
Before todays operation, a total of 33 searches had been conducted in connection with the murder in Northern Ireland, the Republic of Ireland and Scotland.
The latest police investigation is being led by detectives from the Serious Crime Branch.
All five men have been taken to Antrim police station for questioning.
Police said clothing, mobile phones, computers and cars had all been seized for forensic analysis.
Police said a £50,000 reward remains on offer for information leading to the arrest and conviction of those responsible for Constable Kerr's murder.