Twelve days after a pair of blasts turned celebratory cheers into screams of horror at the Boston Marathon's finish line, investigators continued working -- interviewing people and searching for evidence, even when it meant sifting through trash -- to find out why.

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"One of the ways these discs could be reused is as a radiation shield because there's a lot of plastic packaging in the trash, " Mary Hummerick, a Qinetiq North America microbiologist at Kennedy Space Center in Florida working on the project, said in a statement.

MSN: NASA hopes astronaut trash can be used as radiation shield