Boston bombing suspect Dzhokhar Tsarnaev reportedly wrote a note claiming responsibility for the attacks on the marathon one month ago — and stating that he and his brother were motivated by a desire for Muslim retribution for the U.S. role in the wars in Afghanistan and Iraq. Ever the elusive young terror figure, Tsarnaev allegedly penned the note on the interior of the boat where he was found after a day-long manhunt on April 19, and CBS reports that this note will now be used in court. CBS's well-sourced John Miller had the scoop this morning:

Sources tell Miller that Tsarnaev wrote the note in the boat he was hiding in as police pursued him, and as he bled from gunshot wounds sustained in an earlier shootout between police and his older brother.

The note, scrawled with a pen on the interior wall of the cabin, said the bombings were retribution for what the U.S. did to Muslims in Afghanistan and Iraq, and called the Boston victims collateral damage in the way Muslims have been in the U.S.-driven wars. When you attack one Muslim, you attack all Muslims, the note added.

Sources told CNN and NBC News that these were similar to sentiments Tsarnaev expressed in his bedside interrogation in a Boston hospital the next week. But it sounds likely that Tsarnaev thought he was going to die between his bloody escape that Thursday night in Watertown, Massachusetts, and when authorities stormed the boat in an early Friday evening siege. It's already being described as a last confession of sorts. The note doesn't necessarily provide any firm answers as to whether or not Tsarnaev was brainwashed by his brother or if Dzhokhar was more independent than his friends and acquaintances painted him to be — two big questions that may determine what kind of punishment Tsarnaev will face.

Indeed, putting together the puzzle of the younger Tsarnaev's motivation has been difficult, at least in the public's understanding of him. Law enforcement officials have consistently described Dzhokhar as "a suspect who looks more like an agreeable follower of his elder brother's instructions" The Wall Street Journal reports in today's paper. Interviews from Dzhokhar's friends, from both college and high school, seemed to fit this portrait as well. Many of Tsarnaev's friends expressed their shock and disbelief when asked if they thought he was capable of such and attack— some blamed this older brother, Tamerlan. And though Dzhokhar reportedly cited the war retribution in this note on the boat, it remains unclear how much of that kind of influence might have been from within or from his brother. 

What news of the note does offer, of course, is a clearer picture of any true motivation. It also makes clear that investigators have more hard information for a trial than previously believed, since Tsarnaev has largely kept quiet after receiving his Miranda warning. CBS's Miller added, on today's Early Show, that the note will be used in a trial ahead:

The note, says Miller, will be a significant piece of evidence in any Dzhokar trial - it is clearly admissible, and paints the clearest picture authorities have of why the brothers did what the note says they did.

Tsarnaev's next court date is set for May 30.