Gardai are continuing their hunt for three men who robbed a travelling diamond jeweller of €1m of precious stones when they broke into his hotel room.
Officer believe the opportunist raiders had no idea of the value of their haul and could yet be targeted by other gangs looking for a slice of the fortune.
Brave Noah Stefancki (64) was battered on the head with a hammer as he tackled one of the three raiders in the Travelodge Hotel, Ballymun, and chased them into the street before they turned into Coultry Road.
But he failed to prevent them taking his suitcase containing diamonds and rubies.
Mr Stefancki said he had lost his life savings because the jewels were not insured.
Russian-born Stefancki, who lives and works in Southampton, in England, is a regular visitor here and travels around the country for business deals with local jewellers.
Gardai believe he was the victim of opportunistic local criminals who became aware that he was carrying a valuable haul in his suitcase and kept watch on his movements until they established where he was staying.
Investigators are also tracing all known contacts of the jeweller since he arrived in Dublin to try and establish how the gang knew that the contents of the case were so valuable.
Sources say the three-man gang could now become the focus of more serious players in the crime world, especially since the jewels are unmarked in any way, and therefore easier to "fence", because they are not traceable.
Mr Stefancki was in his bedroom at around 12.15am when the three masked raiders, armed with a gun and a hammer, forced their way in.
He lunged at the closest member of the gang and attempted to stop him from grabbing the suitcase. But he was hit twice on the head with the hammer and the gang escaped from the hotel on foot.
They were pursued by Mr Stefancki, who had blood streaming from his wounds, on to Shangan Road but the three then turned into Coultry Road and escaped.
Mr Stefancki immediately returned to the hotel and raised the alarm.
After gardai arrived at the scene he was taken to the Mater Hospital for treatment for lacerations to his head. He was later discharged.