Dead Man Walking author Helen Prejean, CSJ, will speak at Boston College on Sept. 17 at 7 p.m. in Robsham Theater. Sister Helen is a Roman Catholic nun whose prison ministry and advocacy against the death penalty have garnered international attention. She also is the author of the The Death of Innocents: An Eyewitness Account of Wrongful Executions. The event is sponsored by the Church in the 21st Century Center.