CBS News correspondent John Miller says sources tell him that the note was written by Dzhokhar on the interior wall of the boat's cabin, as Dzhokhar was bleeding from a gunshot wound he received earlier that morning.
The note stated that the bombings were in retribution for what the United States had done to Muslims in Afghanistan and Iraq, and calling the bombing victims "collateral damage," much in the way that many Muslims have died during the Iraq and Afghanistan wars.
"When you attack one Muslim, you attack all Muslims," the note said.
Dzhokhar also revealed that he wasn't mourning his brother, Tamerlan, who died earlier that morning, because Tamerlan was already a martyr in paradise by then. Dzhokhar wrote that he soon expected to join him as a martyr.