PUEBLA, Mexico—When Lupita Pérez Parra was a young girl, struggling to learn how to read, her mother would punish her by pricking her fingers with a sewing needle. Years later, when Ms. Pérez became frustrated at her own children, she found herself meting out the same painful punishment.
EL FUERTE, Mexico—One recent day, a line of grieving mothers armed with picks and shovels worked their way across a muddy field looking for Mexico’s dead and missing, their own children among them.
