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(NECN) - There are are no final answers to the motives of the Tsarnaev brothers, but there is informed analysis.
Criminologist James Alan Fox, a professor at Northeastern University, is the author of "The Will to Kill: Making Sense of Senseless Murder", and says he thinks Tamerlan Tsarnaev had immense influence on his younger brother Dzhokhar, but that Dzhokhar also had influence on his older brother.
"As far as the older brother, what we often find in these cases is someone who may have the idea, the ideology, which he did have, but not necessarily was about to do it, but having his brother with him, supporting him," Fox says. "We find it is easier to do despicable acts when you have someone else joining in, supporting you, telling you it's okay, it's the right thing to do."
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