An estimated 4.1 percent of all death row inmates are innocent, according to a study published in the April Proceedings of the National Academy of Sciences. Researchers Samuel Gross, Barbara O'Brien, Chen Hu, and Edward H Kennedy, from the University of Michigan Law School, the Michigan State University College of Law, the American College of Radiology Clinical Research Center, and the University of Pennsylvania School of Medicine, respectively, came up with this stunning figure by using the exoneration rate on death row and extending it to inmates whose capital punishment has been replaced by life imprisonment, at which point efforts to exonerate them largely subside. Currently, about 1.7 percent of inmates on death row are formally exonerated. [read the full story here]