The arrest of Jamie Paulin Ramirez, a 31-year-old mother, confirmed by a U.S. law enforcement source who spoke to Reuters on condition of anonymity, marks the second American woman linked to such a conspiracy in recent days.

The U.S. Justice Department said on Tuesday it has charged Colleen LaRose, a suburban Philadelphia woman who used the online pseudonyms "Fatima LaRose" and "JihadJane," with plotting to kill an unnamed Swedish man and using the Internet to enlist co-conspirators.

Separately, Irish police said on Tuesday they had detained seven individuals suspected of planning to assassinate cartoonist Lars Vilks of Sweden in retaliation for a drawing that depicted the Prophet Mohammad with the body of a dog.

That cartoon is said to have prompted an Iraqi group linked with al Qaeda to place a $100,000 (65, 824 pound) bounty on Vilk's life. Three of those arrested were released late on Friday, police said.

U.S. officials have declined to comment on whether the indictment of "JihadJane," who has been in U.S. custody since last October, was connected with the alleged Vilks plot.

But Ramirez's mother and stepfather, Christine and George Mott of Leadville, Colorado, said they believe their daughter was recruited by LaRose, who they say introduced Ramirez to an Algerian man she married after moving to Ireland in September.

"These terrorists came into my home through he Internet, uninvited, and have ripped my family apa

rt," Christine Mott told Reuters in a telephone interview from the family's home in Leadville, a small, picturesque town in the Rocky Mountains about 80 miles (129 km) southwest of Denver.

SON IN FOSTER CARE

The Motts said their daughter took her 6-year-old son with her to Ireland, and that he had been placed in foster care since Ramirez's arrest on Tuesday with six others, including her newly wed Algerian husband. Her parents described the Algerian as "JihadJane's main contact over there."

The Motts said they learned on Thursday of their daughter's incarceration with six other foreign nationals through a U.S. government official but declined to be more specific.

Neither Irish police, nor the FBI or Justice Department would comment on whether Ramirez was one of those held.

The Motts said Ramirez had been living with her son in their home, and working at a nearby medical centre while studying to be a nurse practitioner, when she stunned relatives last Easter by announcing her conversion to Islam.

Christine Mott said her daughter began spending a growing amount of time on the Internet, conversing online with individuals who seemed to be extremists. She also began covering herself with a traditional head scarf, or hijab, worn by devout Muslim women, her mother said.

In September, Ramirez vanished, prompting the family to file a missing-persons report with local police. George Mott, himself a convert to Islam, said he talked to FBI agents and handed over Ramirez's computer to them as evidence of the parents' concerns that she had fallen in with extremists.

In October, Ramirez called her parents from Ireland to report that she and her son were safe and living there.

Christine Mott said she has talked regularly with her grandson until this week, and was devastated when he told her in a recent conversation that "'We hate Christians,'" leading to a heated quarrel with her daughter over the phone.

She said her main concern now was to get her grandson back to the United States.

Of the four men and three women arrested in Ireland, aged mid-20s to late-40s, police said one man and two women were released in the southern county of Waterford on Friday.

Vilks, who said he has prepared a secure room in his house with barricades in case of any break-in, told Reuters on Wednesday that he had received more death threats through Internet messages since the arrests were made.

In January, a Somali man was indicted on charges he broke into the home of Danish cartoonist Kurt Westergaard and threatened him with an ax. A Westergaard cartoon depicting the Prophet Mohammad with a turban shaped like a bomb sparked outrage across the Muslim world in 2005, with at least 50 people killed in riots in the Middle East, Africa and Asia.

Most Muslims consider any depiction of the founder of Islam as offensive.

(Reporting and writing by Steve Gorman in Los Angeles; additional reporting by Padraic Halpin in Dublin; editing by Anthony Boadle)