Yusuf Kama, who was introduced in "The Crimes of Grindelwald," explains to Credence that Corvus Lestrange used the Imperius Curse to seduce his mother Laurena, away from his father, Mustafa Kama. Laurena eventually died while giving birth to Leta Lestrange.
Yusuf was given a mission before his father's death — to kill the person that Corvus Lestrange loved the most in the world, as revenge for Laurena's death. While Yusuf initially thought this to be Leta, he learned that Corvus did not care for his daughter, nor his next wife. Instead, Corvus only cared for his son, also named Corvus.
Upon learning of Yusuf's task, Corvus sent the child and Leta along with Irma Dugard to travel to America. During the journey, as Leta reveals in the Lestrange family mausoleum in "The Crimes of Grindelwald," she swapped Corvus out for another child, eventually leading to him drowning when the ship sank.
At the end of "The Crimes of Grindelwald," Kama escapes Grindelwald's rally alive, traveling to Hogwarts with Newt, Tina, and company.