Why did Michael kill AnnaLucia and Libby on Lost?

Michael killed Ana Lucia and Libby in "Lost" under the influence of the Man in Black, who manipulated him into believing that he needed to do so to protect his son, Walt. Michael was desperate to reunite with Walt, and the Man in Black convinced him that the deaths were necessary for his escape from the island. This act was a tragic culmination of Michael's internal struggle and the moral dilemmas he faced throughout the series. Ultimately, his actions led to significant consequences for both himself and the other survivors.