The last thing we want to do is have someone get left behind in St.

CNN: STORY HIGHLIGHTS

Basic products like ethylene are the sort of thing that a sophisticated economy like the US should have left behind.

FORBES: Why the US Chemicals Industry is Booming

Ten seconds later, the second blast occurred, and evidence shows the backpack Mr. Tsarnaev left behind in front of the Forum restaurant is the only thing that could have caused the second blast, according to the affidavit.

WSJ: Dzhokhar Tsarnaev Charged by U.S. Prosecutors in Boston Marathon Attack