McCleskey's proof of discrimination rested on a study conducted by David Baldus, in which he examined nearly 2,500 homicides between 1973 and 1979 to determine whether there was racial bias in sentencing. The study used state-of-the-art statistical analysis. The data analysis showed a clearly disproportionate use of the death penalty when victims were white compared to cases in which victims were black. According to the study, nearly 6 of every 10 defendants who were sentenced to death for killing white victims would not have been sentenced to death had their victims been black. Prosecutors sought the death penalty for 70 percent of black defendants with white victims, but for only 15 percent of black defendants with black victims and only 19 percent of white defendants with black victims. In the case of Charles Walker in Illinois, he was white and had killed a young white couple. Not only do studies show that the death sentence is imposed based on the race of the victim, but it tends to be imposed upon defendants with backgrounds of poverty, limited educational opportunity, and families ravaged by the effects of alcohol or drug abuse. Further, advocates for the more extensive use of the death penalty believe the criminal justice system has such safeguards that an innocent person will never be executed. A recent study documented 350 cases in which an innocent person was convicted of a capital crime. Rarely do defendants in capital cases receive the kind of defense that would keep an innocent person from being found guilty. Given the strong support for the expanded use of the death penalty, prosecutors must exercise their discretion properly and without racial bias; judges must not sacrifice the right to a fair trial and due process on the altar of judicial efficiency and docket control; and defense lawyers must continue to represent the accused to the best of their ability.