Aaron Brady, the convicted killer of Detective Garda Adrian Donohoe, was released back to prison without charge on Saturday morning after he was arrested over allegations of witness intimidation related to the murder trial.
Brady was last month sentenced to life imprisonment for the murder of the garda in Co Louth in 2013.
Gardai attached to the Garda National Bureau of Criminal Investigation arrested Brady at Portlaoise Prison on Friday as part of its ongoing investigation into allegations of "witness intimidation, perverting the course of justice and the unlawful use of mobile phones in the prison environment" related to the trial.
There have been seven arrests in relation to the investigation.
