Siraj Ahmed Malik, an ambitious young Pakistani journalist, was enjoying a stint last fall on a fellowship at the University of Arizona when he started getting chilling messages from home. One after another, his friends and colleagues were disappearing, he learned, and their bodies were turning up with bullet holes and burn marks. A doctor’s son from his home town was arrested and vanished. A fellow reporter was kidnapped, and his corpse was found near a river. A student leader was detained, and his bullet-riddled body dumped on a highway. A writer whose stories Malik had edited was shot and killed.