The son of an independent councillor and another man arrested on suspicion of computer hacking which crashed the Fine Gael website have been released without charge.
Donncha Carroll, the son of Offaly councillor John Carroll, was detained yesterday in a raid on his home near Birr in the county, while a second man was held in the Galway area.
Computers and other digital media devices were taken from both men's homes for forensic examination.
The suspects, aged in their late teens, were questioned on suspicion of criminal damage linked to a series of cyber attacks which shut down the Fine Gael site in January and other sites outside Ireland.
Carroll, who completed his Leaving Certificate this summer and designs websites, was held during searches of the family home, a bed and breakfast on farmland in Crinkle, The Ring, just outside Birr.
The hacking investigation was launched after a revamped website for the Fine Gael party was broken into on January 9 and contact details of 2,000 subscribers accessed.
The site - hosted by a US company - was allegedly targeted by the "Anonymous" group, best known for its co-ordinated attacks on companies opposed to the whistleblowing site WikiLeaks run by Julian Assange.
The four-hour attack saw the Fine Gael homepage replaced by a message credited to the Anonymous group and referred to censorship. Hackers are believed to have had access to email, phone numbers and computer details of subscribers.
The FBI was also involved in the investigation. The agency had been called in by American internet firm ElectionMall, which reported the attack to US authorities, to help with inquiries.