The man who was arrested yesterday in relation to the Creeslough explosion has been released without charge.
A file will be prepared for the Director of Public Prosecutions.
The man, aged in his 60s, was arrested for alleged offences contrary to the Non-Fatal Offences Against the Person Act.
Ten lives were lost in the tragedy in October 2022.
Gardaí say that investigations are ongoing, coordinated from Milford Garda station where an Incident Room has been established under the direction of a Senior Investigating Officer.
The investigation continues to be led by local Gardaí in Donegal Division, supported by the Garda National Bureau of Criminal Investigation (GNBCI) and other agencies including the Health and Safety Authority and the Commission for the Regulation of Utilities (CRU).