The family claim they need protection claiming they fear the 46 year old will kill again.
The family contacted Gardai in Donegal but were told Gallagher’s release was a matter for the Mental Health Review Board at the Central Mental Hospital.
Gallagher can now stroll the short distance from his home in Strabane across the bridge at Lifford and visit his elderly mother and brother Christopher at Post Office Lane.
The rest of his estranged family said they are terrified he will strike again now that he has been given the all-clear to cross the border into Co Donegal.
“What are we going to do now. It’s as if our opinion and our fears don’t matter and have never mattered.
“We were given two hours notice that he was to get out and he got out an hour later. What kind of justice is that?
“It was bad enough before that he managed to come across to Lifford under darkness and slip back to his home again.
“Now he can do it in full view of the Gardai and everyone else and doesn’t have a care in the world.
“We’re distraught but nobody seems to be listening to our fears,” said a spokesman for the Gallagher family.
However Gardai say they have no authority to detain Gallagher unless he breaches the conditions of his release.
A senior Garda spokesman said “This is a matter for the Central Mental Hospital Review Board.
“Unless he breaches the conditions of his release then he cannot be detained.”
Gallagher was released on Friday afternoon just weeks after he handed himself back into the hospital from where he absconded in 2000.
He had been living openly in Northern Ireland since 2003 after shooting to death mother and daughter Anne and Annie Gillespie in Sligo Hospital in 1988.
Under the condition of his release he cannot contact any relatives of the Gillespie family or his own estranged family.
He is also prohibited from going beyond a five mile radius of Lifford.
Relatives of the Gillespie family including Patrick Maguire lives approximately 12 miles from the border in Ballybofey.
Mr Maguire, who cheated death when Gallagher’s gun jammed in his face on the night he killed the mother and daughter, was also made aware of the Lifford man’s release.
Gallagher can visit his brother Christopher and his mother at Post Office Lane in Lifford and also his late father’s grave.
A spokesman for the Minister for Justice Alan Shatter said Gallagher’s release, which came just six weeks after he handed himself into the Central Mental Hospital, was not a matter for his office.
The decision was a matter for the Mental Health Review Board and said it would not be appropriate to comment.
Last night a spokesman for the Gallagher family said they believe a ”deal was done” before their brother handed himself into the Central Mental Hospital in May.
“When he handed himself back into the Central Mental Hospital he knew he would be out in a short space of time.
“He had it all worked out and he would never have gone in if he thought he was going to be locked up for a long time.
“He never served a day for killing those two women – he had it cushy in hospital and now he is out.
“Now it’s us who have to serve a life sentence looking over our shoulders wherever we go,” said the family spokesman.