Before the Islamic State, the group commonly known as ISIS, murdered American journalist James Foley, the insurgents sent an email to his family saying they were open to a prisoner exchange for "Muslims currently in your detention."

A woman they specifically mentioned was Aafia Siddiqui. Two weeks after Foley was beheaded, ISIS suggested that it would trade American journalist Steven Sotloff for Siddiqui. There was no deal, and Sotloff, too, was beheaded.

Last month was hardly the first time Siddiqui's name had come up as a bargaining chip. Besides ISIS, the Taliban and other extremist groups have requested her in hostage exchanges.

So just who is Siddiqui and how has she come to matter so much in America's war on terror?

Siddiqui, or Lady Al-Qaeda as she is known in counterterrorism circles, was convicted in 2010 in a Manhattan federal court of trying to kill Americans while she was detained in Afghanistan. The 42-year-old neuroscientist, educated at MIT and Brandeis, is still waiting to appeal the 86-year sentence she is serving in the medical center of the special housing unit at the severe confinement prison at Carswell, Texas.

Faced with claims she was an Al-Qaeda sympathizer and might have worked as one of Osama bin Laden's "facilitators," Siddiqui, a mother of three—Ahmed, Mariam and Suleiman—denied the charges against her at the trial, which included two counts of attempted murder, armed assault, using and carrying a firearm and assault of U.S. officers.

The American prosecutors successfully claimed, in July 2008, that while under interrogation in Ghazni, Afghanistan, Siddiqui grabbed an officer's M4 rifle and began firing. A witness claimed she shouted, "I'm going to kill all you motherfuckers!" and "Death to America."

Her current defense attorney, Tina M. Foster, says there is no forensic evidence linking her to the crime. "There were no fingerprints on the gun," Foster says. In the prosecutors' version, Siddiqui, who is slight, missed her targets, but an officer shot her twice in the gut, wounding her badly. She was then transported by helicopter to Bagram Airfield near Kabul, the largest U.S. airbase in Afghanistan. She was still healing from internal injuries when, on August 4, 2008, the Afghan government transferred her to the United States for prosecution. A month later, she was indicted.

In 2010, Siddiqui went on trial in Manhattan. There, she did herself no favors. She was outspoken, demanding that anyone of Jewish origin be excluded from the jury. "If they have a Zionist or Israeli background…they are all mad at me," she told Judge Richard Berman, who had to ask her to leave the court room at some points because of her outbursts. "They should be excluded if you want to be fair.… This is a verdict coming from Israel, not America, and that is where this anger belongs. I can testify to this, and I have proof."

To one of the Army captains testifying against her, she shouted: "It's ridiculous! You're lying." Her defense team argued there was a lack of evidence, but the jury quickly convicted her. Her murder counts, however, were found not to be premeditated. One member of Siddiqui's legal team at the time, Elaine Sharp, said: "In my view, [the verdict] is wrong. There was no forensic evidence, and the witness testimony was divergent, to say the least. This was a verdict based on fear, not fact."

Four British parliamentarians (Lord Ahmed, Lord Sheikh, Lord Patel and MP Mohammad Sarwar) called the trial a grave miscarriage of justice and demanded Siddiqui's release. In a letter to President Barack Obama, they pointed to a lack of scientific and forensic evidence tying Siddiqui to the weapon she allegedly fired. Groups like the British-based Reprieve took up her case. Personalities such as the former cricketer-turned-politician Imran Khan also rallied behind her. One of her former attorneys described her as "the ultimate victim of America's dark side."

There is chatter—including a recent report on Iran TV—that the United States has agreed to extradite Siddiqui as part of a prisoner exchange, but American officials would not comment on the story. Her family, including her sister, Fowzia, a Harvard-educated neurologist in Karachi, Pakistan, who has mounted a prolonged appeal for her release, told Newsweek they are not getting their "hopes raised" by the reports. A member of her American legal team, Robert Boyle, was also unaware of any new developments in her case.

Even if Siddiqui is eventually returned to Pakistan, her story might never be unraveled.

Siddiqui grew up an upper-middle-class girl in Karachi, a city on the Arabian Sea that has been a hotbed of terrorism because of its proximity to the porous Afghan border, the Persian Gulf and its vast seaport. She was raised in a sprawling, bougainvillea-strewn villa, the daughter of a physician and his wife, a homemaker, in Gulshan Iqbal, an enclave of Karachi.

There, Fowzia met with a Newsweek reporter at her childhood home, where she now lives—along with her own family and Ahmed, the eldest of Siddiqui's children, and Mariam, the middle child. The youngest, Suleiman, is believed dead, accidentally dropped when Siddiqui was allegedly abducted by Pakistani intelligence in 2003. A smiling MIT graduation photo of Siddiqui hangs on the wall, near placards that call for her release: "Lincoln's dream, justice for all," one reads. "Why Aafia denied."

Fowzia said she remembers her little sister as smart and gentle. "She would not hurt an ant," she said. "She was so sensitive that she could not bear an animal in pain. It would make her go pale. If she had a balloon and it burst, she cried. My mother used to tell her to play with balls, not balloons, so she would not get so upset."

When Siddiqui's brother, Mohammed, a pediatrician, moved to Texas in 1990, she followed him to complete her studies, attending the University of Houston. She then went to MIT, where she majored in biology, before beginning her Ph.D. at Brandeis in cognitive neuroscience. Her fellow students and teachers remember her as studious, soft-spoken and pious. It was during university that she became interested in radical Islam.

Her professors, when questioned after the trial, said her academic work centered on how human beings imitate others. "I can't see how it can be applied to anything," Paul Di Zio told Boston magazine after her arrest. "Calling her a mastermind or something does not seem—I never saw any evidence."

An Aafia Siddiqui supporter carries silk roses as she gets her picture taken next to a poster during celebrations to mark Siddiqui's 41st birthday in Karachi March 2, 2014. Akhtar Soomro/Reuters

By the time she finished her Ph.D., she was married to a Karachi doctor, Mohammed Ajmad Khan, also studying in Boston. The couple and their two small children lived on the 20th floor of a modern building near the Boston hospital where he worked as an anesthesiologist. Neighbors remember her as quiet, and a devout Muslim wife and mother. "She was an American girl and a good sister," says Abdullah Faruuq, the imam of a mosque next to their apartment.

Siddiqui did charitable work in the Muslim community, including raising money for Bosnia and Chechnya war victims. "She was an activist in the purest sense of the word," her sister said. "She would raise money for old women's homes, for public parks and for Bosnian refugees."

But there is another, far darker side to the story. By 2001, the FBI was already suspicious of Khan and Siddiqui because of their donations to Islamic charities that the bureau was watching closely. There was also a series of unusual Internet purchases—$10,000 worth of body armor, night goggles and military books. According to Foster, those were for Khan to go hunting in Pakistan.

Saying life for Pakistanis was becoming too difficult in the U.S. in the aftermath of 9/11, the couple returned to Karachi. There, Siddiqui gave birth to their youngest child, but a few weeks later they divorced. Khan would later tell The Guardian that Siddiqui was too radical for him and "so pumped up by jihad."

A Newsweek reporter caught up with Khan in Karachi. He is an orthodox Muslim with a long black beard and still a doctor. He insists that he is not an extremist. He said his ex-wife insisted the couple leave the U.S. and go to Afghanistan, where the American attacks had already begun. He said she was furious at him for "not doing jihad in Afghanistan," and they divorced soon after.

Khan also told Newsweek that Siddiqui maintained a post office box in the U.S. that was later used by Al-Qaeda operatives, although that never came up in her trial.

Siddiqui's family and legal team dismiss Khan's claims as nonsense, calling him an "abusive husband" who became vindictive after she left him. "He also wanted the children," says Foster. "So he would say anything."

Back in Karachi, Siddiqui took her children to live in the family home with her mother and sister. The spring of 2003 was the last time Siddiqui's family saw her. They say she put her children—then 7 years, 5 years and 6 months old—into a taxi to go to the airport to fly to Islamabad to visit a relative. But she was stopped en route to the airport.

Her supporters say her disappearance is connected to the capture and interrogation of one of the masterminds of the 9/11 attacks, Khalid Sheikh Mohammed, on March 1 2003. The Guardian and other media have linked her—although her family denies this—to Mohammed because it is said she married his nephew.

Although Mohammed's interrogation was kept secret, The Guardian later reported that during the course of numerous waterboardings, he gave up Siddiqui's name. Foster denies this.

Fowzia expresses pain when she talks of her sister's disappearance. "Aafia left home for the airport [to take the flight to Islamabad] along with her three children, then [the next thing we knew] two men on motorcycles came and told my mother she had been taken and not to cause trouble," she says.

Siddiqui was not heard from again until 2008. Her supporters say she was the victim of rendition, transported by the Pakistani security service, the Inter-Services Intelligence (ISI), to secret prisons and safe houses in Pakistan and Afghanistan, where she was held and subjected to interrogation and abuse.

Pakistani Aafia Siddiqui is seen in a February 3, 2010 courtroom sketch in New York CityReuters TV/Files

The Siddiqui family then hired Foster, who has defended other prisoners who have been in Bagram Airfield and has an understanding of how Pakistani intelligence agencies work. Some reporters claimed that Siddiqui's original lawyers were fired because they were Jewish, but Foster says it was because they were retained and paid by the Pakistani government and hence did not investigate anything that might be incriminating to the state. According to Foster, her client was taken to various safe houses between 2003 and 2008 and was often drugged during the transfers.

On July 17, 2008, she turned up in Ghazni. According to Foster, she arrived by bus, having been given a bag by her captors that was said to contain the items that would incriminate her. Foster contends that the plan was to make her appear to be a suicide bomber, planted in front of the governor's mansion. It was likely she would be shot and killed, which would solve an ISI problem, the lawyer maintains.

In Ghazni, Foster also says, Siddiqui had been given a bag containing Nivea jars containing gel-like substances and forced—she says she was told her captors would rape her daughter if she did not do it—"to write names of New York landmarks." Those were the documents and materials she was found with when she was captured.

In no way, Foster says, did she take the American officer's gun and begin shooting wildly. What is true is that she was shot, nearly died, and was taken to Bagram to be operated on. She was then flown to America—which Foster says is akin to an illegal extradition.

The U.S. government and prosecutors tell an entirely different story, insisting that during the "lost years" between 2003 and 2008 Siddiqui was at large, plotting attacks for Osama bin Laden. In 2004, John Ashcroft, the U.S. attorney general, listed her among the seven most wanted Al-Qaeda fugitives. She was described as "armed and dangerous."

In this account, she was detained by Afghan police in Ghazni on July 17, 2008, after they found her carrying handwritten documents for a "dirty bomb" and the list of New York landmarks, as well as sodium cyanide in Nivea jars.

When the FBI agents and soldiers arrived to interrogate her further, she was waiting behind a yellow curtain. The agents' version is that she suddenly grabbed an officer's gun and began shooting. She was, according to one of the witnesses, Captain Robert Snyder, "a vision of hatred…shooting at us. Shooting at me."

The court report states that while Siddiqui was recuperating at Bagram—where critics say abuse was commonplace—she was tethered to the bed with soft restraints, but always able to use a button to call for help, use the bathroom or get food and water. She had a female security detail with her for eight hours a day, with whom she sometimes had lucid conversations. Several weeks into her recovery, still in pain from her wounds, she was flown to America to stand trial.

She was evaluated to determine whether she was psychologically fit to stand trial. One of the court psychiatrists, Dr. Leslie Powers initially determined that Siddiqui was not competent because she was having hallucinations, according to federal records. Powers then revised her assessment, according to the records, finding that Siddiqui was "malingering to avoid prosecution."

And what about her second marriage, which ties her to Khalid Sheikh Mohammed, who is now held in Guantanamo Bay?

According to The Guardian, who investigated the Siddiqui case in Pakistan in 2010 before her trial, "Six months after her divorce she married Amman al-Baluchi, a nephew of…Khalid Sheikh Mohammed, at a small ceremony near Karachi." The Guardian claims the marriage has been confirmed by Pakistani and U.S. intelligence, and by FBI reports filed by Siddiqui herself, in court.

Her family, supporters and lawyer vehemently deny this, and say the marriage never took place. "She never did a second marriage!" Fowzia told Newsweek. "She hardly completed her iddah—[a four-month period of celibacy when a Muslim woman becomes widowed or divorced]—from her first marriage when she was picked up."

During and after her trial, Siddiqui's stature grew in some circles to that of La Passionara, the romantic Spanish Civil War heroine. British activist Yvonne Ridley—a former journalist who was incarcerated in Afghanistan during the Taliban time and later converted to Islam—has taken up Siddiqui's case. Ridley explains how Siddiqui has become iconic in the Muslim world, symbolizing the bias many Muslims have experienced post-9/11. "People are angry with American imperialism and domination," Ridley told The Guardian.

Tauseef Ahmed Khan, a liberal and secular scholar in Karachi who is also a professor of mass communication at the Federal Urdu University, also has a theory as to how she became a cause célèbre and why the jihadists are so keen to release her: "After the 9/11 war on terror, most of the Pakistanis believe that America is against the Muslims. So whether she is guilty or not, I believe that America should release her on humanitarian grounds. These issues are used by the extremists to arise the sentiments of Muslims."

"It's very political and very significant," says Mauri' Saalakhan of the Peace Thru Justice Foundation, which is based in Maryland and is working on Siddiqui's case. He says he is utterly convinced of her innocence.

But if she is innocent, why do the world's most dangerous terrorist groups want her so desperately?

"That's easy to answer," says

Saalakhan. "She has come to symbolize what is wrong with this so-called war on terrorism, and has become an international symbol.

"[What is unclear] is whether these groups [ISIS and the Taliban] are doing this out of sincerity—because she is a Muslim woman being held under conditions which violate international law and U.S. Constitution on cruelty," he says.

Saalakhan says it's "not just Al-Qaeda calling for her release. Former U.S. attorney general Ramsey Clark is also calling for her release.

"To understand why ISIS [and other groups] want to trade her so desperately, you have to understand how popular she is in Pakistan," says Foster, explaining how she has become a larger-than-life symbol of injustice that ISIS is manipulating for its benefit.

Still, the offers to trade her were refused. The U.S. government, which does not make concessions to terrorists, flatly refused the Foley-Siddiqui swap.

The Obama administration insists that it is not prepared to barter—or even to discuss bartering hostages for Siddiqui. "I'm not going to get into any alleged internal deliberations and what ideas may have been generated, if any, on this issue," White House spokeswoman Caitlin Hayden told Foreign Policy magazine when asked about the Foley case.

"Aafia Siddiqui is serving a sentence of 86 years in prison for the attempted murder and assault of U.S. nationals and U.S. employees in Afghanistan. The United States government, as a long-standing policy, does not grant concessions to hostage-takers. Doing so would only put more Americans at risk of being taken captive," Hayden said.

Fowzia says the deals being proposed by ISIS involving her sister are "very absurd and weird. They are just capitalizing the issue. Where were they when Aafia was missing for years? They are just bringing bad name to Aafia while talking of exchanges and ransoms."

According to Saalakhan—who was authorized by the family to speak to Newsweek—Siddiqui is not doing well in prison, physically or mentally. "She is not being treated as well as the other prisoners," he says.

Foster says that Siddiqui is sometimes in solitary confinement for up to 23 hours a day; she is unable to contact her family and has been attacked by other prisoners. "She's tiny…like a little mouse," says Foster. "And she is in this place with some…very hardened women."

The family has not been in touch with Foster since December 1, 2013, when they asked her to work on the appeal, which they hope to resume.

When her family told Siddiqui this, she just replied: "Do you think it will make any


Additional reporting in Karachi by Ashraf Khan.