The Special Criminal Court is holding a so-called "trial within a trial" to decide on the admissibility of certain evidence relating to the Regency Hotel murder.
David Byrne was shot dead when a tactical team dressed as armed Gardaí stormed a boxing weigh-in at the Dublin hotel in February 2016.
The non-jury court is dealing with the evidence of two detectives who identified the accused Patrick Hutch from a photo taken at the scene.
Before the three judges can rule on the admissibility of their evidence, they must first hear it.
Detective Garda Jonathan Brady from Mountjoy Garda Station told the court he was 100% sure it was Mr Hutch when he was shown the image of a man dressed as a woman at Ballymun Garda Station the day after the shooting.
His partner, Detective Garda Fergal O’Flaherty, said he also immediately recognised the person in the photo, but didn't openly name him when he first saw it.
They both said they were familiar with Mr Hutch after investigating another incident in 2014 when the now 25-year-old from Champion’s Avenue in Dublin was shot in the leg.
He was charged with David Byrne’s murder on the prosecution’s belief he participated in and shared the intent to commit the crime.
He denies the charge.
Our Courts Correspondent Frank Greaney reports: