A suspect who was identified for making menacing phone calls to Environment Minister Alan Kelly was yesterday ruled out of the investigation.
Officers had investigated a local man in Nenagh, Co Tipperary, for making a bomb threat call to Mr Kelly's constituency office on Monday morning. But yesterday gardai said they were satisfied that the suspect was not involved in the threats.
"He was looked at but he has no case to answer. Phone records are being studied and gardai are taking this matter seriously," a senior source said last night.
No arrests have yet been made.
The bomb threat is one of four sinister threats that the embattled Minister has had to endure this week.
Menacing calls were made to both his Dail and constituency offices on Wednesday.
A caller claimed that they would "shoot the minister in the head".
And they come after the hoax bomb alert at his Nenagh, Co Tipperary office on Monday.
Another caller on Tuesday warned that "a bullet would be put in his head".
After the four death threats, new security arrangements have been put in place at the Department of Environment's HQ at the Custom House in Dublin city centre.