Hagerman Horse Documentary BOISE, ID (idaho) - It's a mystery scientists are still trying to solve. Why did hundreds of horses die in southern Idaho two million years ago? Hundreds of fossils of the Hagerman Horse have been found in one small area, but no one knows why. Now, a new documentary by a local filmmaker tries to put the pieces of the puzzle together. Boise State Public Radio's Samantha Wright saddles up to take a closer look. © Copyright 2012, idaho