BOSTON (AP) — Lawyers for Boston Marathon bomber Dzkokhar Tsarnaev rested their case in his federal death penalty trial Tuesday after presenting testimony designed to show his late older brother was the mastermind of the 2013 terror attack.The defense admitted during opening statements that Tsarnaev participated in the bombings. But Tsarnaev's lawyer said he was a troubled 19-year-old who had fallen under the influence of his radicalized 26-year-old brother, Tamerlan, who died following a shootout with police days after the bombings.Prosecutors and Tsarnaev's lawyers will give closing arguments April 6.