A teenage boy has been arrested and questioned about mobile phone footage of another teen being assaulted, stabbed and mocked while he was lying covered in blood on the ground.
He was arrested at his home and taken to Togher Garda Station in Cork under Section 4 of the Criminal Justice Act 1984.
He was released without charge on Tuesday and a file will now be prepared for the Director of Public Prosecutions.
Two other teenagers - both known to the teen arrested - were also questioned under caution.
Gardai said they are "very pleased" with the response to their public appeal for information about the alleged incident at Waterpark in Carrigaline at 10.30pm on Saturday night.
A 17-year-old boy was treated in Cork University Hospital after suffering stab and slash-type injuries in the incident.
The injuries to his back and head were not life-threatening and the youth has since been discharged, though he may require ongoing medical treatment.
Another 17-year-old boy - who cannot be identified for legal reasons - has been charged before Cork District Court with assault causing harm and robbery of a mobile phone.
The teen was remanded on bail with strict conditions and will appear again before Cork Children's Court next month.
Under the terms of his bail, he must stay away from all social media platforms, reside at a stipulated address, sign on at a garda station in Cork and agree to stay out of three specified areas of Cork.
He has also been told to have no contact with a number of named individuals.
The camera phone footage of the incident - with the blood-covered and helpless youth being mocked while lying injured on the ground - sparked outrage across the country.
The family of the injured teen paid tribute to the local community and emergency service personnel for the overwhelming support they had received since Saturday evening.
Both gardai and Cork civic leaders have appealed for the video footage not to be shared online out of respect for the teen and his family.
Gardai have harvested large quantities of material from various social media platforms in relation to the incident.
They have asked anyone who witnessed suspicious behaviour in the Waterpark area last Saturday night to contact them in strictest confidence.
They have also appealed for any motorist whose vehicle is equipped with a dashcam and who drove through Carrigaline between 7pm and 11pm last Saturday night to come forward.
Gardai are also studying CCTV footage from the area.
A detailed file will be prepared for the DPP.