A man has admitted stabbing four children to death at a kindergarten in Uganda, saying he believed killing them as human sacrifices would make him wealthy, prosecutors said on Wednesday.The defendant, Christopher Okello Onyum, 39, who holds both Ugandan and American citizenship, appeared in court to have the charges formally put to him.He is thought to have gained access to the kindergarten by posing as a parent, before attacking children with a knife, killing four of them – ranging in age...