US photographer Scott Langley began documenting the death penalty more than 20 years ago, after he was moved by an experience he had standing outside a prison "death house" in his native Texas. His photos are currently on display at the 8th World Congress Against the Death Penalty, which is taking place this week in Berlin. They aim to expose the "inhumanity" of capital punishment by allowing people to imagine the executions, which take place behind closed doors, often in the dead of night. Langley joined us for Perspective to discuss why the United States remains an outlier when it comes to the death penalty, and what he would say to the families of victims who wish to see perpetrators executed.