He came to the U.S. legally in 2008 to study chemical engineering at Texas Tech University. He was arrested in Lubbock in February 2011, after federal agents secretly searched his apartment and found explosive chemicals, wiring, a hazmat suit and clocks, along with videos showing how to make the chemical explosive TNP.

Aldawsari wrote in his journal that he had been planning a terror attack in the U.S. for years, even before he came to the country on a scholarship, and that it was "time for jihad," or holy war, according to court documents. He bemoaned the plight of Muslims and said he was influenced by Osama bin Laden's speeches.

FBI bomb experts have said the amounts of chemicals in the case would have yielded almost 15 pounds of explosive -- about the same amount used per bomb in the 2005 London subway attacks. He also tried to order phenol, a chemical that can be used to make explosives.

Prosecutors said other targets he researched included nuclear power plants and the homes of three former soldiers who were stationed at Abu Ghraib prison.