The defense strategy is to try to convince jurors to spare Mr. Tsarnaev the death penalty by arguing that his older brother, Tamerlan, was the driving force behind the attacks, and that they would not have occurred had it not been for Tamerlan.

At the end of deliberations on Tuesday, the jurors sent a note to the judge asking questions about aspects of the lengthy verdict form they are using. The jury form, which is more than 30 pages, asks jurors to reach a verdict on each count, and there is a sequence of follow-up questions.

One question asked by jurors on Tuesday was whether a ''conspiracy'' can be about a distinct event or something that takes place over a longer period. The judge, George A. O'Toole Jr., told the jurors that the scope or duration of a conspiracy was a question that they must determine.
