Ensnared in a Texas law that makes accomplices subject to the death penalty, Mr. Foster, 30, is to become the third death row inmate this week, and the 403rd since capital punishment resumed in Texas in 1982, to give his life for a life taken. But unlike most others condemned to death in this state, Mr. Foster, a former gang member and aspiring musician and now a prison poet from San Antonio, is not a murderer in the usual sense. He was convicted and sentenced to die for abetting a killing — 80 feet away — that he might, or...