A federal magistrate judge has appointed a prominent specialist in federal death penalty cases to join the defense team of alleged Boston Marathon terror bomber Dzhokhar Tsarnaev. Judy Clarke, a San Diego, Calif., attorney, has the “background, knowledge and experience” that will “enable her to provide adequate representation to the defendant,” US Magistrate Judge Marianne Bowler said in a ruling today. Clarke’s clients have included Unabomber Ted Kaczynski; Susan Smith, who drowned her two children; and most recently Tucson, Ariz., shooter Jared Loughner. All received life sentences instead of the death penalty, The Associated Press reported. Bowler denied, for the time being, a request for the appointment of a second death penalty specialist for the defense team. Tsarnaev, 19, faces charges of use of a weapon of mass destruction and malicious destruction of property resulting in death. He and his brother, Tamerlan, are accused in the April 15 bomb attacks on the mara