Here are five stories we have on our radar today:
1. Boston bombings: Investigators are continuing to search for answers after Monday's bombings at the Boston Marathon, and details about the victims are becoming known. One severely injured man, whose photo has become one of the iconic images of the disaster, has deep roots in Philly and South Jersey. More coverage: The scene in Boston on Tuesday, why race security is hard to guarantee, how to help, a Temple doctor's story.
2. Ricin letter: A letter sent to Mississippi Sen. Roger Wicker is believed to have contained ricin, a potentially deadly poison. Further tests are being done, and fellow Sen. Claire McCaskill says a suspect has been identified.
3. Library merger: The Free Library of Philadelphia Foundation and Rosenbach Museum Library are working on a merger. Details still need to be negotiated, but current plans call for the Rosenbach to become a subsidiary of the Free Library by the end of June.