Isabel dos Santos is Africa’s richest woman, worth an estimated $3 billion. She has amassed a global empire of businesses, luxury apartments, and artwork, and built a reputation as a self-made woman who succeeded through hard work and determination. But new reporting by investigative journalists has revealed she may have used secrecy and her government connections to help amass her fortune. Those connections included her father, who was president of Angola for 38 years until he stepped down in 2017....