"World News Tonight With David Muir" Podcast - May 15, 2015

Amtrak 188 - Tragedy on the Tracks: Major developments in the crash with new surveillance video of just seconds before the train derailed and what the engineer has revealed to federal investigators. 

Boston Marathon Bombing Trial: Convicted marathon bomber Dzhokhar Tsarnaev was sentenced to death and eyewitnesses int he courtroom say Tsranaev never looked at the jury and showed no eotion as the verdict was read. 

Missing US Helicopter Found: A US Marine helicopter sending aid to victims of the earthquake in Nepal that vanished has now been found and there are no survivors. 

Remembering B.B. King: The blues legend passed away and the world his remembering his special sound and profound influence on the world. 

Principal Makes Controversial Remarks: A principal in Georgia is underfire for making controversial remarks at graduation.