By Allison Elyse Gualtieri"48 Hours" will air "The Trial of Alex Murdaugh" Saturday at 10/9c. His presence at the murder scene was uncovered thanks to a cellphone video taken by his son, in which Alex Murdaugh's voice could be heard shortly before the killings near the kennels on their rural Colleton County estate on June 7, 2021. Maggie Murdaugh, 52, was shot four or five times with a rifle, and 22-year-old Paul was shot twice with a shotgun