 -- A third American hostage held by ISIS has been identified as a 26-year-old American woman who was kidnapped a year ago while doing humanitarian relief work in Syria. The terror group is demanding $6.6 million and the release of U.S. prisoners for the life of the young woman, whom a representative for the family requested not be identified.

She is the third of at least four Americans who were known to be held by ISIS, the Islamic State of Iraq and Syria. American journalist James Foley was executed by the group in a video that appeared online last week. Another writer, Steven Sotloff, was seen alive but under duress in the same footage.

In addition to the multi-million dollar ransom, the terror group has also demanded that the U.S. release Aafia Siddiqui, an MIT-trained neuroscientist who was convicted by the U.S. in 2010 of trying to kill U.S. officials two years before, according to a supporter of Siddiqui who has been in contact with the hostage’s family.

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Siddiqui’s release has been a regular demand of groups critical of U.S. policy in the Middle East and Southwest Asia, but Monday Siddiqui’s family spoke out through supporters to say they were “very distraught” Siddiqui’s name was invoked with the ransom request and sought to distance themselves from ISIS.

“If the issue is true, we would like to state that our family does not have any connections to such groups or actions,” reads a letter written by Siddiqui’s family. “We believe in a struggle that is peaceful and dignified. Associating Aafia’s name with acts of violence is against everything we are struggling for.”

“While we deeply appreciate the sincere feelings of those who, like us, wish to see the freedom of our beloved Aafia, we cannot agree with a ‘by any means necessary’ approach to Aafia’s freedom. Nor can we accept that someone else’s daughter or sister suffer like Aafia is suffering,” the letter says.

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The Siddiqui family has been “traumatized by the thoughts that someone else could be harmed in the name of Aafia,” said Mauri Saalakhan of the Peace and Justice Foundation, who held a sparsely attended press conference Monday and spoke on behalf of the Siddiqui family.

“They’re opposed to it. In their letter to ISIS they made it very clear, this is not the way, these are not the conditions under which we want our loved ones released,” Saalakhan said. “Nor did they want harm to come to anyone else’s loved one in the name of Aafia… They conveyed that message loud and clear.

“The most important message that I could convey to ISIS or whoever it is that’s holding these innocent people captive abroad is that at the end of the day, this type of approach in response to an injustice that you feel, is not only not the inappropriate way to go, but, properly understood, it is a violation of the tenets of the faith that we claim to believe in,” he said. “We just have to do the right thing because it is the right thing, without any strings attached.. And the right thing would be to let this young woman go back to her family, go back to her life. And the right thing for America to do, for our government… would be to do the same with Dr. Aafia Siddiqui.”

The details of the ISIS ransom demand and the abduction of the young aid worker were disclosed by Saalakhan and a close friend of the unnamed hostage family in statements to ABC News Monday.

Each of the three known surviving American hostages in ISIS’s hands have been threatened with death since Foley’s execution, sources have told ABC News. In the video that showed Foley’s death, a masked militant said that Sotloff’s fate rested in President Obama’s hands – an apparent demand that the U.S. stop airstrikes against ISIS targets in Iraq.

The day after Foley’s execution video emerged online, the U.S. military announced it had continued bombing runs against ISIS in Iraq and overnight The New York Times reported President Obama has approved surveillance flights over Syria, what the paper called a potential precursor to airstrikes there.

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