Remember John Walker Lindh? One of America’s first detainees in the war on terror walked out of prison today after serving seventeen years of a 20-year sentence for terrorism. Reports that Lindh spent time in prison evangelizing for violent Islamist radicalism has some questioning why the federal government let him out ever:

John Walker Lindh, the so-called “American Taliban” whose capture in Afghanistan riveted a country in the early days after the September 11 attacks, has been released from prison.

After serving 17 years of a 20-year sentence, Lindh, the first US-born detainee in the war on terror, on Thursday walked out of a federal prison in Terre Haute, Indiana, and will join the small, but growing, group of Americans convicted of terror-related charges attempting to re-enter into society.

Lindh will live in Virginia subject to the direction of his probation officer, his lawyer, Bill Cummings, tells CNN. But some are already calling for an investigation into his time in prison — where he is said in two US government reports to have made pro-ISIS and other extremist statements — that could send him back into detention.

Reports of Lindh’s maintained radicalization, detailed in two 2017 official counterterrorism assessments, are also driving questions about the efforts of the US government to rehabilitate former sympathizers like him, who are expected to complete prison sentences in waves in the coming years.

Lindh’s behavior must have been particularly good, at least from the prison system point of view. Federal guidelines require prisoners to serve at least 85% of their sentence regardless of their disposition while incarcerated, and that’s precisely what Lindh served. Even so, Lindh would have been released no later than three years from now regardless of his behavior, unless he committed other prosecutable crimes while in prison.

The father of America’s first post-9/11 casualty in the war on terror has been fighting a losing battle to keep Lindh behind bars at least for those three years. Johnny Spann, whose son Johnny “Mike” Spann was killed in a prison riot just an hour after attempting to interrogate Lindh, tried appealing all the way to the White House to force Lindh to stay in prison. “I feel like we failed him,” Spann says about his son and the man whom Spann believes is responsible for his son’s death.

ABC News reports in a profile of Spann that Lindh has done a little more in prison than just make some pro-ISIS statements, too:

Some who have known Lindh, or have spoken to officials inside the U.S. government, said leaked assessments published by Foreign Policy in 2017 by the National Counterterrorism Center and Bureau of Prisons accurately portrayed Lindh as even more radicalized than when he was captured on an Afghan battlefield in 2001.

Lindh has even sermonized to small groups of fellow Muslim inmates at Terra Haute, according to one source with direct knowledge, where he cited the words of Sayyid Qutb, an Egyptian Muslim Brotherhood ideologue in the 1950s whose writings inspired those who later created al Qaeda.

Spann said he worries that Lindh could somehow become an influencer to extremists because “he is an icon,” and so this year he pressed Sen. Richard Shelby, R-Ala., to take up the matter with the White House. In an ABC News interview on Sunday, the still-grieving father delivered a direct appeal to President Donald Trump to somehow find a way to halt Lindh’s release after having served 17 of 20 years with time off for good behavior.

“Mister president, please do your job,” Spann said.

If Lindh was still flogging radical and extremist views with other inmates while in prison, that might raise questions about what the prison system considers “good behavior.” It could also raise questions about freedom of speech and exercise of religion, but it’s tough to see how being pro-ISIS would be a religious exercise of any kind. It’s worth noting that the conditions of Lindh’s release would technically prevent him from conducting such activities outside of prison. If that’s the case, then why did conducting those activities in prison have no effect on his good-behavior standing?

Nevertheless, Trump likely couldn’t have done much under the circumstances. An attempt to order Lindh’s continuing incarceration would have almost certainly been shot down by the courts, as good-behavior remission is a statutory exercise. Absent disciplinary action by prison officials, that time collects automatically. The real problem is that Lindh was undercharged. He should have been charged with treason, or at least with complicity in Spann’s death. Either or both would have kept Lindh in prison for the rest of his life, or even invoked the death penalty. Given the charges for which Lindh was convicted, his release was inevitable. And that’s also true for many others in similar positions to Lindh as well.

Indiana can heave a sigh of relief that Lindh won’t live among them. As CNN notes, Lindh will move to Virginia, but what part of Virginia? Er …

In fact, Lindh, 38, will not only be set free, he will have to live somewhere outside of Washington, in the eastern part of Virginia, under supervised release when he leaves the U.S. penitentiary in Terre Haute, Indiana, three sources told ABC News.

That’s only a place with lots and lots of military and government operations, even outside the confines of DC. What could go wrong? If we’re lucky, we’ll never have to find out, but … I don’t think we’re that lucky.