Marathon Bombing: Investigators say the Boston bombs were made of pressure cookers filled with explosives, ball bearings and nails, then placed in black duffle bags. Using a pressure cooker is a known technique for improvised bomb making around the world.

Investigators have asked the public for tips and video. They went to Logan airport to ask departing visitors for quick downloads of their finish line video. Although the bombings have been described as an act of terror, Homeland Security Secretary Janet Napolitano said there was no indication they were part of a larger plot. Contrary to early press reports, authorities say they did not recover any unexploded devices.

The dead have been identified as eight-year-old Martin Richard, and Krystle Campbell, 29, a restaurant manager. The boy’s seven-year old sister lost a leg, and his mother has a serious head injury. The third fatality is a Chinese graduate student at Boston University whose family asked that she not be identified. Seventeen of the injured are listed in critical condition.

National: Expanded background checks for gun buyers are not likely to pass the Senate, according to West Virginia Democrat Joe Manchin. Not enough Republicans support the bill to reach the 60% majority.

➢A letter mailed to Republican Sen. Roger Wicker of Mississippi has tested positive for the deadly toxin ricin. The letter has been identified as being mailed from Memphis by someone who frequently writes to legislators.

Indisputable Torture: An independent review of prisoner treatment at Guantanamo Bay during the Bush administration concludes that, “it is indisputable that the United States engaged in the practice of torture”. The report by the Constitution Project says prisoners were waterboarded, chained in uncomfortable positions, and deprived of sleep, among other things. Defenders of those techniques say they are not torture.

World: China issued a national defense report revealing that it has just under 1.5 million people in the armed forces and a budget about one-seventh of what the US spends on the military. China deployed its first aircraft carrier only last September.

Obit Page: Pat Summerall, a former place kicker who became the television voice of pro football, died in Dallas at age 82. Summerall paired for 21 years in the booth with the effusive John Madden. He once kicked a 49-yard field goal in a snowstorm to send the NY Giants to an NFL championship. He played 10 years for the Chicago Cardinals and the Giants, but left his mark on the game with his gentlemanly voice.

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