A man in his 40s arrested in connection with the fatal shooting of 39-year-old Mark Cullen in South County Dublin has been released without charge, An Garda Síochána confirmed on Saturday.

Mark Cullen died on the morning of Sunday, 5 July 2026, after sustaining fatal gunshot injuries in Patrician Park, located off Kill Avenue in Dún Laoghaire. Emergency services attended the scene, where he was subsequently pronounced dead.

Investigating officers detained the suspect on Thursday, 10 September, as part of their ongoing homicide probe. Following questioning, the man was released from custody, and Gardaí stated that a file will be prepared for submission to the Director of Public Prosecutions.

An Garda Síochána emphasized that inquiries into the fatal shooting remain active. Gardaí continue to appeal for anyone with relevant information, dashcam footage, or CCTV recordings from the Patrician Park and Kill Avenue areas on the morning of the incident to contact Dún Laoghaire Garda Station.