Accused Boston Marathon bomber Dzhokhar Tsarnaev, who was found hiding in a boat days after the blasts, left a handwritten message describing the attack as retribution for U.S. wars in Muslim countries, CBS News reported on Thursday.

The CBS News report, citing anonymous sources, said that Tsarnaev used a pen to write the message on an interior wall of the boat, where police found him bleeding from gunshot wounds four days after the April 15 bombing.

The note summed up with the idea that “when you attack one Muslim, you attack all Muslims,” CBS News reported.

CBS News did not make clear how its sources knew the information and Reuters was not immediately able to confirm the report.

A spokeswoman for the FBI in Boston, Katherine Gulotta, declined to confirm or deny the report.

The CBS News report said Tsarnaev, 19, described his older brother and fellow suspect Tamerlan Tsarnaev, 26, who died in a gunbattle with police, as “a martyr.”

“Basically, the note says … the bombings were retribution for the U.S. crimes against Muslims in places like Iraq and Afghanistan and that the victims of the Boston bombing were ‘collateral damage,’ the same way innocent victims have been collateral damage in U.S. wars around the world,” said CBS News reporter John Miller, who is a former spokesman for the FBI.

The bombings at the finish line of the world-famous marathon killed three people and injured 264 others. The FBI identified the ethnic Chechen brothers as suspects from video and pictures at the scene.

Dzhokhar Tsarnaev was arrested in Watertown, Massachusetts, on April 19 after a daylong manhunt and lockdown of much of the Boston area. He is being held in a prison hospital west of Boston and faces charges that could carry the death penalty if he is convicted.

Tamerlan Tsarnaev had been on a U.S. government database of potential terrorism suspects and the United States had twice been warned by Russia that he might be an Islamic militant, according to U.S. security officials.

(Reuters)