John Walker Lindh, better known as the “American Taliban,” has been released from prison after serving 17 years of a 20-year sentence. Lindh was the first U.S.-born detainee in President George W. Bush’s “war on terror” and his capture in Afghanistan brought him to national attention in the aftermath of the 9/11 attacks. He was raised near San Francisco and traveled to Pakistan in 2000 to train with a radical Islamic group before moving to Afghanistan and joining the Taliban. U.S. troops first encountered Lindh in November 2001. He was initially charged with conspiracy to kill U.S. nationals, but later struck a deal with prosecutors and pleaded guilty to fighting alongside the Taliban. On Thursday, he walked out of a federal prison in Terre Haute, Indiana, and will now live in Virginia, according to CNN. But there have been calls to investigate his time in prison, where he is accused of making pro-ISIS statements that could ultimately send him back into detention.