A terrorism expert has testified that a note Boston Marathon bomber Dzhokhar Tsarnaev (joh-HAHR' tsahr-NEYE'-ehv) wrote explaining the 2013 attack used themes of global jihad similar to those in materials found on his computer.

At Tsarnaev's federal death penalty trial Monday, Matthew Levitt compared Tsarnaev's note to extremist materials found on his computer. Those included issues of Inspire magazine, an al-Qaida publication, and audio lectures by Anwar al-Awlaki, an American-born Muslim cleric who was killed in a U.S. drone strike in Yemen in 2011.

In his note, Tsarnaev wrote that the bombings were carried out as retaliation for U.S. actions in Muslim countries.

Levitt is expected to be cross-examined Tuesday by Tsarnaev's lawyers.

Tsarnaev's lawyers have admitted he participated in the bombings, but said his older brother, Tamerlan, was the mastermind.