Police in the Irish Republic have released a fourth person, an American woman, who was detained over an alleged plot to murder a Swedish cartoonist, BBC reported.
The woman, who has not been officially named, was among seven people arrested. Three were freed without charge on Friday. Three men are still being held.
They were suspected of planning to kill Lars Vilks over a cartoon of Prophet Muhammad's head on the body of a dog.
It was used in a 2007 Swedish newspaper editorial on freedom of expression.
Those originally detained included nationals from Algeria, Libya, the Palestinian territories, Croatia and the US.
The American woman arrested in Ireland has been named by US media as Jamie Paulin-Ramirez.
Christine Mott, from Colorado, identified Mrs Paulin-Ramirez as her daughter, whom she described as a "very insecure, unhappy person that just was looking for something to hang on to".
Irish police have refused to confirm whether Mrs Paulin-Ramirez is the woman involved, and have declined to release the identities of any of those arrested.
The woman, a 31-year-old mother, is the second American woman linked to the alleged plot.
US officials said on Tuesday that they had charged Colleen LaRose, a Philadelphia woman, with plotting to kill an unnamed Swedish man and using the internet to enlist co-conspirators.
Ms LaRose - who described herself online as "Jihad Jane" - was detained last October in Philadelphia.
Unconfirmed reports say she travelled to Ireland in September and met some of the seven suspects arrested there on Tuesday.
Mrs Mott said she believed her daughter was recruited by Ms LaRose, who introduced her to an Algerian man she married after moving to Ireland in September.
In 2007, a group linked to al-Qaeda in Iraq offered a $100,000 (£66,000) reward for killing Mr Vilks, and a 50% bonus if he was "slaughtered like a lamb" by having his throat cut.
The Vilks cartoon was published about a year-and-a-half after a series of depictions of the Prophet Muhammad in Denmark's Jyllands-Posten paper caused protests by Muslims around the world.