A fresh appeal for information has been made 11 years after the murder of Andrew Allen in Co Donegal.
The 24-year-old, who was originally from Derry, was shot in front of his partner at his home in Links View Park, Buncrana, on 9 February, 2012.
Gardaí believe that a number of people were involved in the murder, destruction of evidence and later sheltering the killers.
In a statement, gardaí said a number of people have been arrested and questioned in connection with the investigation.
Officers believe there are still people in both Buncrana and Derry city who have information that may assist in bringing those responsible to justice.
They are appealing to anyone with information, however insignificant it may seem, to come forward.
Anyone with information is asked to contact the incident room at Buncrana Garda Station on 074-9320540, the Garda Confidential Line on 1800-666-111 or any garda station.