Lisa Smith's solicitor has insisted there's no evidence the jihadi bride has been involved in terrorism.
The Co Louth woman, 38, is being quizzed at Kevin Street Garda Station for a second day.
It follows her return to Ireland, after landing at Dublin Airport on Sunday alongside her two-year-old daughter.
Darragh Mackin, who is representing Smith, said that the garda case against her is “inherently weak”.
He said: "I think it’s clear that she does not pledge allegiance to the terrorist organisation ISIS. That was her case publicly."
He added: "There’s absolutely no evidence that she’s been in any terrorist organisation or terrorist group."
She was arrested on suspicion of terrorism offences and may be held until Wednesday.
The former Defence Forces member converted to Islam in 2011, then quit the Air Corps and in 2015 travelled to Syria, through Tunisia.
And Mr Mackin also said that going to a particular location is not a crime.
Speaking on RTE's Morning Ireland, he said: "There are extreme organisations that target vulnerable people on the basis of their religious beliefs to lure them to certain areas.
"Going to a particular location is not a terrorist offence."
It’s understood Smith was married four times and the child’s father was a British jihadi who was killed while fighting for the group.
Smith worked on the Government jet while in the Air Corps and accompanied former president Mary Robinson and Taoiseach Bertie Ahern.
Smith and her daughter were put into a camp for ISIS widows and children on the Syrian border.
She escaped last month following the Turkish invasion before she was picked up and handed over to Turkish officials
She arrived on Sunday on a Turkish Airlines flight and was accompanied by two members of the Army Ranger Wing and officials from the Department of Foreign Affairs.
