Uber investor Shervin Pishevar revealed a lot more details on Thursday about the infighting going on within Uber's board. In a biting letter to the board of directors, Pishevar accused investor and board member Benchmark of taking advantage of the personal tragedy in Travis Kalanick's life to oust him as the company's chief executive. He's referring to a boating accident in May that killed Kalanick's mother and injured his father. Kalanick was on a leave of absence from Uber in June when a contingent of investors, lead by Benchmark, demanded his resignation.