In 1915, a German Spy Bombed the U.S. Capitol

At almost midnight on July 2, 1915 a bomb ripped through the U.S. Capitol. At the time, it was the most violent attack on the halls of Congress since the British torched the building during the War of 1812. The next morning, as police in Washington analyzed a note left by the bomber, financier J.P. Morgan, Jr. was shot at his home on Long Island. Was it possible that the same man was responsible?