The suspect, who is aged in his 40s and is a businessman, has already been arrested and questioned about a campaign of abuse against Co Longford-based Senator Micheál Carrigy.
As part of the long-running investigation, officers based in Granard Garda Station have seized a phone and other electronic devices.
Senior sources say the suspect had been allegedly in contact with the politician for more than three months, and gardaí are confident of being able to bring a harassment charge before the courts.
“It seems that this started out as abuse on social media late last year about the senator’s stance on how Covid was being regulated,” a senior source said last night.
“This then expanded into threatening text messages and then sinister threats against the man’s family and even references to his young children.
“He made a complaint to gardaí in February and this matter was dealt with promptly as there were indications that the matter was escalating.”
As part of their detailed inquiry, gardaí had to consult external senior barristers before a file was sent to the DPP.
When contacted for comment, Senator Carrigy confirmed the case was under investigation and said: “This is in the hands of the gardaí now”. He then said he did not want to speak about the case.
Gardaí have made very significant progress in their investigation after analysing various seized devices after the arrest of the suspect in February, the Sunday World has learned.
The man is understood to be an outspoken social media campaigner against the Government’s response to the Covid-19 pandemic. The Co Longford man allegedly started abusing and threatening Senator Carrigy during Christmas.
“What was said to the senator was simply unacceptable and criminal in nature,” a senior source said. “When his family were brought into it, he involved the gardaí and things seem to have stabilised since then.
“We are not talking about a criminal mastermind here. All the alleged offending texts were sent from that individual’s own mobile phone, which has been examined in full.”
Sources said the criminal harassment campaign has taken a severe toll on Senator Carrigy and his family.
Research was published early this year which indicates many Irish politicians are on the receiving end of threatening or lewd anonymous letters and phone calls.