The suburban Chicago mother of a 19-year-old American facing a terrorist charge for trying to join the ISIS militants accused the group on Tuesday of brainwashing youths into joining their ranks via social media. And she declared, "Leave our children alone!" Mohammed Hamzah Khan's mother cried softly as she read her statement in a lobby at a Chicago federal courthouse. Minutes earlier, her son had pleaded not guilty to attempting to provide material support to a foreign terrorist group. It carries a maximum 15-year prison term. Zarine Khan, flanked by her husband, Shafi, said her family felt compelled to speak out in the wake of "unspeakable acts of horror" in Paris last week that killed 17. One gunman reportedly pledged allegiance to the ISIS group, while two others cited al-Qaida. "The venom spewed by these groups and the violence committed by them ... are completely at odds with our Islamic faith," the 41-year-old mother said. She added, "We condemn the brainwashing and recruiting of children through the use of social media and the Internet."

Khan, who lived with his parents, was arrested in October at O'Hare International Airport as he sought to board an international flight in Chicago on the first leg of a plan to sneak into Syria to join ISIS militants, court documents allege.

Weeks later, prosecutors revealed that Khan's 17-year-old sister and 16-year-old brother were also detained at the airport and allegedly also aspired to live under ISIS control. The younger siblings were interviewed by the FBI but haven't been charged. According to court documents, the girl once used the Twitter handle @DeathIsTheeNear to send a favorable tweet about a video of beheadings - placing a smiley emoticon in the text. The younger siblings haven't been charged.

Investigators later found a three-page letter in Khan's bedroom in which he apologized to his parents for leaving so abruptly. But he added he felt obliged to go from disgust with Western society and from anger over U.S.-backed bombing of ISIS fighters, court filings alleged.

"This nation is openly against Islam and Muslims," he wrote. Adept ISIS propagandists managed to woo Mohammed Khan into falsely believing they had established a legitimate Islamic government in parts of Syria and Iraq, Khan's lawyer, Thomas Durkin, told reporters Tuesday. "He's a very devout, committed, thoughtful kid who bought into some very slick advertising," Durkin said. Khan's mother ended her statement before a dozen reporters and TV cameras by directly addressing ISIS and its leader, Abu Bakr al-Baghdadi. "We have a message for ISIS, Mr. Baghdadi and his fellow social media recruiters," she said, raising her voice. "Leave our children alone!"