Gardaí have been investigating since 2012.
A press spokesperson for An Garda Síochána has renewed the organisation's appeal for information regarding the murder of Andrew Allen.
On 9 February 2012 Andrew Allen was murdered in his home at 26 Links View Park, Buncrana, Co Donegal in front of his partner.
Gardaí are certain that those responsible travelled to Buncrana from Derry City that evening.
The latest statement from Gardaí reads "If you have any information in relation the killers Gardaí are asking you to do the right thing and come forward to assist in securing justice for Andrew."
The statement also noted that "many people have been arrested and questioned over the past seven years and An Garda Siochana are grateful for all those who have assisted the investigation."
Anyone with information is encouraged to contact the incident room at Buncrana on 074 93 20540 or use the Confidential line 1800 666 11.
