They won't answer any questions until the deed is done so to speak, but after, if approached respectfully, will explain the ritual to someone they believe to be a 'nomad from the tunnels'. It was the Witch's time, you see, she was already dying. When someone from the city is about to die, the great wish is to hold out long enough to return to the moss that gives them protection, a way for their spirit to live on in the membranes that surround the city. Witches especially are honored to give the last of their magic to it. They will explain that she wanted this, and they were given the great honor of seeing her off and remembering her life.