A man arrested by detectives investigating the murder of Denis Donaldson, a British spy inside the IRA, has been released pending a file being sent to prosecutors.
The man, aged in his 40s, was detained on Thursday for questioning about the April 2006 killing.
Mr Donaldson, 55, a Sinn Fein official and close colleague of party president Gerry Adams, was shot dead at an isolated cottage near Glenties in Co Donegal.
A Garda spokesman said the arrested man was released without charge and a file would be prepared for the Director of Public Prosecutions (DPP).
Last month, a pensioner from Scotland was granted bail after he was charged with withholding information in relation to the same investigation.
Another man, in his 40s, was arrested and then released, also pending a file being sent to prosecutors.
Mr Donaldson had been living in a remote area of Donegal following his exposure as an MI5 agent a year before his death.
Dissident republican group the Real IRA claimed responsibility for the murder in 2008 but the circumstances surrounding Mr Donaldson's outing as a British agent and subsequent death have long been shrouded in mystery.
A long-delayed inquest into the shooting has been adjourned almost 20 times.
Gardaí have repeatedly urged the coroner to postpone the probe, citing concerns it might compromise their criminal investigation.
In 2014, the Gardaí made a mutual assistance request to a police force outside the Irish Republic in a bid to gain what it described as potentially "significant" evidential material.
That material was secured in March this year.
Investigating gardaí have reissued an appeal for anyone with information about the murder to get in contact.