Long before Aafia Siddiqui allegedly tried to kill U.S. agents and military officers in Afghanistan, the MIT-educated neuroscientist once plotted to assassinate former presidents George H.W. Bush, Jimmy Carter and Bill Clinton, government sources told FOXNews.com.

According to sources, Siddiqui was concocting a plan to use biological agents to contaminate former president Carter's water.

"This was very serious, the investigations will go on for some time," a government source told FOXNews.com.

Those allegations are part of a federal complaint filed on July 31 by the U.S. Attorney Michael Garcia in Manhattan.

According to the complaint, Siddiqui, who attended MIT as an undergraduate and earned her Ph.D. in neuroscience at Brandeis University, was carrying detailed chemical and biological weapons information when she was arrested in Afghanistan.

Siddiqui, 36, was stopped on July 17 outside a government building in central Afghanistan's Ghanzi province by police who suspected that she might be a suicide bomber, a source said, not realizing that she was being sought by the FBI.

Authorities found recipes for radioactive, chemical and biological weapons and explosives, documents detailing U.S. military assets, excerpts from the Anarchists Arsenal, a bomb-making handbook, and one-gigabyte thumb drive, now being analyzed by technology experts, inside Siddiqui's purse, according to the criminal complaint and government sources.

Police also found maps of Ghazni, including the provincial governor's compounds and the mosques in which he prayed, governor spokesman Sayed Ismail Jahangir said.

Authorities believe she entered the country from Pakistan, crossing at the Chaman border post into the southern Kandahar province, Jahangir said. She spent two days in Kabul before going to Ghazni.

The next day, as a team of FBI agents and U.S. military officers prepared to question her, Siddiqui grabbed a rifle, pointed it at an Army captain and yelled that she wanted blood, prosecutors said.

An interpreter pushed the rifle aside as she fired two shots, which missed, they said. One of two shots fired by a soldier in response hit her in the torso.

Even after being hit, Siddiqui struggled and shouted in English "that she wanted to kill Americans" before the officers subdued her, the complaint said.

Siddiqui, a mother of three who was once identified as a possible Al Qaeda associate, was extradited to New York last week to face charges she tried to kill U.S. agents and military officers during the interrogation, federal prosecutors said.

Siddiqui's family attorney, Elaine Whitfield Sharp, called the charges "a tall story." The family claims that after she vanished with her three children while in Pakistan in 2003, she was secretly held and possibly tortured before U.S. authorities finally brought charges to justify her detention.

Sharp disputed the U.S. government's earlier claims that Siddiqui had gone underground for several years before her capture.

"I believe she's become a terrible embarrassment to them, but she's not a terrorist," Sharp said. "When the truth comes out, people will see she did nothing wrong."

A woman who answered the phone at the Mosque for the Praising of Allah, in Roxbury, M.A., where Siddiqui was an active member during her time in Boston, said she was surprised by the news of Siddiqui's arrest and alleged involvement of terrorist activities.

"I'm shocked that this is the same girl I knew," she said, adding that Saddiqui was active in the mosque's Dawa Resource Center, which distributes Korans to prison inmates and provides Islamic-based counseling.

Siddiqui made her court appearance on Monday in a wheelchair, but a Manhattan Federal Court judge delayed the session so she could receive medical treatment for her injuries, WCBS880.com reported.

At a 2004 news conference, then-Attorney General John Ashcroft and FBI Director Robert Mueller III identified Siddiqui as one of seven people the FBI wanted to question about suspected ties to Al Qaeda.

Though they never alleged she was a full-fledged member of Al Qaeda, authorities said they believed Siddiqui could be a "fixer," someone with knowledge of the United States who supported other operatives trying to slip into the country and plot attacks.

Siddiqui is charged with one count each of attempted murder and assault. If convicted, she could face up to 20 years in prison on each charge.

The Associated Press contributed to this report.