NEW YORK (CBSNewYork) -- New evidence has emerged in the Boston Marathon bombing investigation that could become the centerpiece in the case against the surviving suspect in the attack.
Miller said the handwritten note was found scribbled on the interior wall of the cabin, reading as part confession and part suicide note.
"What the letter or the writing on the wall literally demonstrates is motive, a level of commitment and his own involvement," Miller said.
The note stated the bombings were retribution for what the U.S. military did to Muslims in Afghanistan and Iraq and called the Boston bombing victims "collateral damage" in the same way Muslims have been in American-led wars. "When you attack one Muslim, you attack all Muslims," Tsarnaev wrote.
Liz Norden is the mother of two Boston bombing victims. Her sons Paul and J.P. each lost legs. Paul was released from the hospital Friday, CBS 2's Dick Brennan reported.
She said can't believe Tsarnaev could refer to the victims as collateral damage.
"I think it's disgusting," Norden said. "These people are all human beings and it was a cowardly, senseless act. I just can't imagine how they could do something to innocent people, just twisted."
Miller said part of the message shows Tsarnaev thought he was going to die on the boat.
"What the note says, he understands his brother is dead but he doesn't mourn his loss. He believes his brother is a martyr in paradise. He also believes he will join him there," Miller said.
While Tsarnaev confessed many of the same details to the FBI, those admissions came during the 16-hour period he was interrogated before being read his Miranda rights, CBS 2's Weijia Jiang reported.
If there is a legal battle over what information is admissible in court, the note is expected to serve as a powerful piece of evidence for prosecutors, Miller said.
"This miniature manifesto written on the hull of the boat serves as a backstop for his statements. They essentially parallel each other," Miller said.
There was speculation Tsarnaev's defense attorneys would argue his involvement in the bombings was as a follower and under the influence of his dominant older brother, 26-year-old Tamerlan Tsarnaev, but the note shows Dzhokhar's beliefs and justification for the attack in his own words, Jiang reported.
The brothers are suspected in the bombings that left three people dead and more than 260 injured at the finish line of the Boston Marathon on April 15.
After the attack, officials said the two planned to come to New York City to detonate their remaining explosives in Times Square, but they were unable to carry out their attack.
Tamerlan Tsarnaev was killed in a shootout with police; Dzhokhar Tsarnaev was captured alive on April 19 after a massive manhunt. He is in a federal prison and faces a charge of using a weapon of mass destruction to kill.
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