According to court papers, suspects Azamat Tazhayakov and Dias Kadrybayev destroyed and concealed Dzhokhar Tsarnaev's backpack and laptop computer.
The charges say that the suspects decided to conceal the items after learning he was a suspect in the Boston Marathon Bombing.
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Four men are being interrogated in Spain's National Court over the vehicle attacks that killed 15 people and wounded more than 120 others.