Under the law, prosecutors are not required to prove that a defendant had any part in committing a crime, or even intended to commit it. Jurors only need to find that there was a plan to commit a crime and that the defendant should have anticipated that the crime would occur. In Wood’s case, he was sitting in a pickup outside a Texaco convenience store in Kerrville, Tex., in January 1996, when Daniel Reneau went inside and shot and killed the store clerk with a .22-caliber handgun. Dr. James Grigson was no stranger to capital murder cases: By the time Wood went on trial, in 1998, Grigson said he had testified in 163 such cases. Prosecutors often sought his testimony to secure the ultimate punishment for defendants. Often, they were successful, earning Grigson a nickname: “Dr. Death.” Grigson didn’t personally examine Wood.