(CNN) -- When Dzhokhar Tsarnaev got a text from a friend asking him if he was one of the two men shown in FBI-released photos of Boston bombing suspects, his reply was short and light: LOL. Other messages from the teenager followed, including "You better not text me" and "Come to my room and take whatever you want," according to an FBI affidavit released Wednesday. His friend took the texts as jokes, as if Tsarnaev found humor in the mere idea that he could be responsible for such horror. But when Dias Kadyrbayev showed one of their mutual friends that last text, the friend wasn't laughing.
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Three friends of Boston bombing suspect Dzhokhar Tsarnaev are charged in federal court
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Affidavit shows actions, communications after Boston suspects' photos went out
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The friends went to Tsarnaev's dorm, found a backpack with fireworks with the powder out
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They took this backpack and threw it away, the affidavit released Wednesday states
@placeholder's roommate let them in, saying Tsarnaev had left a few hours earlier, according to Kadyrbayev.
Kadyrbayev said he took Tsarnaev's laptop computer too, because he felt @placeholder's roommate might get suspicious if they left with the backpack alone, the affidavit states.