A relative of a man who has been missing since gardai received information someone was thrown off a cliff has been approached for DNA.
Investigators are liaising with the PSNI who contacted the family member as the huge search in the Slieve League area of Donegal continues into a fourth day.
Gardai are also examining fresh information received that the missing 67-year-old had been targeted after he was seen with large amounts of cash in the Killybegs area last week.
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But they have not ruled out that he could have been attacked over a personal row which escalated over the weekend. Another line of inquiry being looked into is that the man was beaten with a rock in the Slieve League area before he vanished.
A male in his 30s and a woman in her 20s were arrested on Monday over the alleged assault on the missing man but were released without charge. The missing man had been staying with the two suspects before his disappearance.
A blood splattered car has been seized while a house remains sealed off and is being examined by forensics.
A source said: “This case is moving all of the time with relevant matters being investigated.
“The gardai are confident they know the missing man’s identity and are working with the PSNI as part of that aspect of the case.
“Significant evidence has been gathered along with information. There are suspects who have been identified.
“But the victim is missing and no body has been found. So it is a complex investigation which remains as an assault one as it stands.
“But that’s not to say it will not be upgraded once it develops even further.”
Gardai have appealed for anyone with information to come forward.