GardaÍ are confident the detective who shot a criminal dead during a foiled robbery in Lucan last Friday will be cleared of any wrongdoing.

The Sunday Tribune has learned that the officer, who is attached to the secretive National Surveillance Unit (NSU), fired five shots at Gareth Molloy and Keith Murtagh after Molloy discharged a round from a sawn-off shotgun.

Both men were hit twice and 27-year-old Molloy died later in hospital from his injuries. Murtagh, 26, is in intensive care but is expected to survive.

Gareth Molloy had put a gun to the head of a Securicor employee and threatened to shoot him dead prior to the exchange of gunfire.

At least five independent witnesses have given statements that they clearly heard the garda say "armed gardaí, drop your weapons" prior to discharging his firearm.

The Garda Síochána Ombudsman Commission (GSOC) has launched an investigation into the fatal shooting and it is understood the office is concerned that both raiders were shot, though only Gareth Molloy was armed. However, garda sources say the incident was over in under five seconds and there was little time for the detective to know this once he was shot at.

Justice minister Dermot Ahern has strongly supported the actions of the gardaí.