GARDAI investigating the fatal stabbing of John Maguire last month say they have not yet identified a prime suspect for the savage murder.
But they acknowledge that a man, who was high on their list of people to interview, has left the country and is now thought to be back home in Brazil.
The man, who is in his 30s, was spotted on CCTV walking with Mr Maguire in Dublin's north inner city on the morning of the murder on August 23.
Camera footage also showed the two men together on the street in the days previous to the stabbing.
Gardai said last night that the Brazilian was one of a number of men they wanted to trace in the immediate aftermath of the frenzied attack.
But they were unable to find his whereabouts until they received intelligence indicating that he had been living on the northside of the capital.
Gardai later called to the house and found that he had left. Subsequent inquiries among the friends of the missing man established that he left Dublin and flew to London on the evening of the attack.
He travelled to Brazil the following day.
Gardai seized a number of items from his home for a detailed technical examination, including clothing, shoes, a home computer and an iPad.
Officers said last night that while they were anxious to talk to the Brazilian they were not following a definite line of inquiry.
Mr Maguire (51) was found slumped behind the front door of his home at Ormond Square in Smithfield with multiple stab wounds to his upper body.
Officers have been trawling through CCTV footage as well as carrying out door-to-door inquiries among neighbours.
Gardai say there is no evidence of a break-in at the house and are satisfied that the motive for the vicious stabbing was not robbery. They think it is more likely that Mr Maguire had known his killer.