“We write to express concern over the anticipated release of convicted American Taliban fighter John Walker Lindh and request information about what steps the U.S. government is taking to ensure public safety,” Shelby and Hassan wrote in their Friday letter. “Mr. Lindh was captured in Afghanistan in 2001, and the following year, he pled guilty to serving as a soldier of the Taliban. Mr. Lindh was sentenced to twenty years in prison but is scheduled to be released early from federal custody on May 23, 2019.”

As a U.S. citizen, Lindh became among the most visible of all the Taliban fighters taken into custody in the aftermath of the September 11 attacks. But Shelby and Hassan said in their letter that their concerns with the Bureau of Prisons about the potential for early release do not end with him.

“As many as 108 other terrorist offenders are scheduled to complete their sentences and be released from U.S. federal prisons over the next few years. Little information has been made available to the public about who, when, and where these offenders will be released, whether they pose an ongoing public threat, and what your agencies are doing to mitigate this threat while the offenders are in federal custody,” the senators wrote.

Aside from asking why Lindh is due to be released before serving the full 20 years, the senators want to know, “How many prisoners in federal custody convicted of terrorism related crimes, or who are categorized as extremist, will be released between now and 2025? Where will they be relocated?”

They also want to know what is being done to reduce the risk of recidivism.