FILE - This file photo released Friday, April 19, 2013 by the Federal Bureau of Investigation shows Boston Marathon bombing suspect Dzhokhar Tsarnaev,    (AP Photo/Federal Bureau of Investigation, File)

Penalty phase opens in Boston Marathon bombing trial

The life-or-death phase in the trial of Boston Marathon bomber Dzhokhar Tsarnaev opened Tuesday with a prosecutor telling the jurors they will come to know the four people killed and “why their lives mattered.”