Wildlifeofficialsin theUnited Statesare trying to determine whatcausedmore than 1,000 blackbirds to fall dead from the sky over asmall town in Arkansas.
While the wood in the study was placed there by scientists, wood naturally finds its way into the ocean as dead trees fall into rivers and are swept out to sea, when storm debris is taken by surging waters and even from shipwrecks.
Muhammad and Malvo each have been charged with one of the attacks in Maryland, northern Virginia and the District of Columbia last fall that left 10 people dead and four wounded.