 The prior probability that they died of natural causes should be compared to the prior probability that a mother would kill them. To have a rough idea, suppose that in a mid-size country like the United Kingdom 1 million babies are born every year of whom 100 are murdered by their mothers. So the chance that a mother would kill one baby in a year is 1 in 10,000. What is the chance that the same mother kills two babies? Say we appeal to the (controversial) assumption of independence. On this assumption, the chance that a mother kills two babies equals 1 in 100 million. Assuming independence,