Boston Marathon Bombings: Suspect Dzhokhar Tsarnaev left message in boat calling victims "collateral damage"

(CBS) -- Boston Marathon bombing suspect Dzhokhar Tsarnaev left a note claiming responsibility for the April attack, describing it as retribution for U.S. wars in Afghanistan and Iraq, reports CBS News senior correspondent John Miller.

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The message was handwritten on the interior wall of the boat where he hid from authorities, bleeding from gunshot wounds, several days following the attack, sources told CBS.

In the note, Tsarnaev described the bombing victims as "collateral damage," CBS reports. "When you attack one Muslim, you attack all Muslims," Tsarnaev wrote. He described his brother Tamerlan, who died in a shootout with police, as a martyr.

The note could be a significant part of evidence in any trial because it paints a picture of the motive for the attacks "consistent with what he told investigators while he was in custody," Miller said Thursday on "CBS This Morning," CBS reports.

Some of the same details Tsarnaev admitted to authorities while in custody were "during the time he was interrogated but before he was given his Miranda warning," Miller said.

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