►National Public Radio's blog on Monday's Boston Marathon bombings discusses the latest information on the construction of the explosive devices. Pieces of one bomb have been sent to Quantico for analysis. According to NBC News, "Investigators said their hunt for suspects and a motive in the attack on the Boston Marathon was 'wide open' and disclosed the first details about the two bombs explosives housed in metal containers, concealed in bags and packed with tiny nails to maximize the carnage. The lead investigator for the FBI, Richard DesLauriers, made a passionate plea for help from the public: 'Someone knows who did this,'" he said.
►The Washington Post reports that police have identified a suspect in the mailing of letter containing ricin to Senator Roger Wicker (R-MS). Senator Claire McCaskill (D-MO) attended a classified briefing and later said that the sender was a person who writes "a lot of letters to members." The envelope, which reportedly contained a white, granular substance, was discovered on Tuesday. Primary tests indicated ricin, but the substance is now undergoing further testing by the FBI.
►The bombs that exploded in Boston were contained in ordinary kitchen pressure cookers. The New York Times reports on this type of bomb, which has been used before in terrorist attacks, and discusses why the bomb makers favor it. "Pressure cookers, which are heated on stove tops and use pressured steam to speed up the cooking of items like lentils or chickpeas, were used in the Mumbai train blasts of 2006 that killed more than 100 people, a blast in Varanasi in 2006 that killed five, and they were believed to have been used in 2005 blasts in Delhi’s Sarojini Nagar neighborhood that killed dozens. Outside India, a pressure cooker was used in a March 2010 blast in Pakistan that killed six, in the attempted bombing in New York’s Times Square in 2010 and to target Western troops in Afghanistan, among other incidents," says the Times. CBS News reports that warnings were issued about pressure cooker bombs as far back as nine years ago. In 2010, the U.S. Department of Homeland Security and the FBI jointly released a pamphlet on the bombs in 2010.
► According to the Detroit News, "Michigan's U.S. Rep. Candice Miller questioned a decision by the Homeland Security Department to add Saudi Arabia to a list of countries whose citizens can travel more easily to the U.S.... Miller and several panel members wrote to Homeland Security Secretary Janet Napolitano two weeks ago asking why Saudi Arabia was being added to the small number of countries involved in a trusted-traveler program offering their citizens easier entry to the United States, with faster passage through passport controls." Miller noted that 15 of the 19 9-11 hijackers were Saudis.