Authorities said there was never any danger to the D.C. Metro system because they were keeping a close watch on Young.
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Young was well-known to counterterrorism investigators, authorities said. Two of his acquaintances pleaded guilty to terrorism charges, and Young has been under investigation for years.
Court records show that Young traveled to Libya in 2011 and sympathized with Nazis and Islamic extremists. If convicted, Young faces a maximum sentence of 20 years in prison.
This video includes clips from ISIS, WRC-TV and WTTG.