As the first police officer to face terrorism charges in the United States goes to trial in federal court this week, FBI special agents and undercover operatives explained to jurors how they began investigating Young in 2010 — and why he was not arrested until August 2016. It was then that Young bought Google Play gift cards that prosecutors say he thought would be used by Islamic State recruits to download encrypted messaging applications.

During the years-long investigation of the Alexandria, Va., native, several law enforcement officials testified, Young repeatedly made violent remarks that were concerning but did not prompt immediate action. Prosecutors said a sting operation involving the gift cards was necessary to get a dangerous radical not just off the streets, but also out of law enforcement.

An FBI agent will testify that “he didn’t sleep at nights because [Young] had talked about torturing and killing an FBI agent,” Assistant U.S. Attorney Gordon Kromberg told the judge Tuesday.