Australian police sent a detective to Ireland to follow up a lead on a gunman suspected of shooting British tourist Peter Falconio in the outback.
However, they say it is no longer a line of inquiry.
Mr Falconio has been missing and presumed dead since he and his girlfriend Joanne Lees were ambushed by a gunman on the Stuart Highway, 190 miles north of Alice Springs on July 14.
Joanne, 27, from Huddersfield, has told police the gunman flagged down their Volkswagen van. She said she heard a gunshot before she was tied up by the man. She later escaped and hid in scrub, but did not see her boyfriend again.
Police found DNA belonging to Mr Falconio and a third person thought to be the gunman on the shirt worn by Joanne when she was attacked.
Northern Territory police said Gardai had contacted them with a possible match to the DNA found on Joanne's shirt.
"There was a possibility that there may have been a match but that didn't eventuate and it is no longer a line of our inquiry," Police Crime Commander Col Hardman said.
Mr Hardman did not say how the detective was able to rule out the Irish DNA but said it did not involve interviewing a suspect.
Mr Falconio's disappearance has led to one of the biggest manhunts ever launched in Australia, with police using aircraft, helicopters and even Aboriginal trackers to search for traces of the missing man and gunman.