Police investigating the dissident republican murder of policeman Ronan Kerr and other terror offences have released a man they arrested in Milton Keynes.
The young Police Service of Northern Ireland constable was killed in a booby trap bomb attack in Omagh, Co Tyrone, in April last year.
The 22-year-old man from Omagh was detained in Buckinghamshire on Monday.
He was released last night without charge.
A 39-year-old man arrested in the Omagh area by officers investigating the murder was released without charge on Tuesday night.
Police investigating the crime conducted a number of searches in the Dromore area of Co Tyrone last night.
In recent days they have also conducted searches in the Omagh area and Cumbria.
Several items were seized for examination, including a lorry stopped in Milton Keynes.
Mr Kerr was from a nationalist background, brought up in a village near Omagh, and his killing caused revulsion among members of the local community.
Dissident republicans have killed policemen, soldiers and a prison officer as part of their campaign to disrupt the peace process and the threat level in Northern Ireland remains severe.