Our gov knew exactly what was going on with Tamerlin Tsarvaev. We knew he left to train with jihadists in the Republic of Kyrgyzstan in 2012. When he came back, his passport had expired but we let him back in no questions asked. Explain that one. Russia warned us about him. England warned us about him. His uncle and father in law are CIA.
Can’t be explained accept as you say, CIA. They recruit college kids always have.