Four men were still being detained by gardai this morning for questioning about the IRA's murder of Det Garda Jerry McCabe in Adare on June 7th, 1996.
The men, all from the midlands, were questioned on matters 'relative to the investigation of the murder', according to Chief Supt Michael Fitzgerald, the senior officer in charge of the case.
The men were arrested in a series of co-ordinated actions by officers in Offaly and Laois yesterday morning. They are being held in Henry Street station and one in Roxboro station under Section 30 of the Offences Against the State Act, which allows their detention without charge for 48 hours.
So far, gardai have arrested and questioned 56 people in the south-west and midlands about the murder of Det Garda McCabe, who was shot as he sat in his patrol car while guarding a post-office cash delivery.
His colleague, Det Garda Ben O'Sullivan, was also shot but has since recovered from life-threatening wounds.
There was no indication last night that the men would appear in court.
It is understood the investigation has expanded to cover the wider activities of the Provisional IRA organisation in the south-west and midlands which contained a number of highly militant figures.
Gardai are still looking for two IRA men believed to have been beside the Garda car when the shooting took place. It is believed they may have fled the country and are being sheltered by IRA supporters, possibly in the US or on the Continent.