It sounds like he aided a terrorist organization to commit murder and kidnappings. If he is a US citizen he deserves due process under the law. If he is not a US citizen, he should be immediately returned to his nation of origin. He can apply for citizenship from there, and the decisions about if he is a terrorist can be made before re-admission.
He is a US citizen.
But of course, Israel green-flagged it—and nothing has come of that for them.