Two men arrested in connection with the murder of Constable Ronan Kerr in Northern Ireland have been released unconditionally.
A man aged 27 was arrested in Omagh and a 40-year-old were taken into police custody from prison on Tuesday.
The Police Service of Northern Ireland (PSNI) officer, 25, was killed by a booby-trap car bomb in Omagh, Co Tyrone, on April 2 2011.
Dissident republicans opposed to the peace process calling themselves the New IRA have been blamed for the attack on the Catholic new recruit outside his home.
The bomb was attached under his car and it exploded as he prepared to drive to work.
Constable Kerr was dubbed a "modern-day hero" by then PSNI chief constable Matt Baggott.
He was the second policeman killed after the PSNI was formed out of the Royal Ulster Constabulary in 2001.
He had joined the police in May 2010.