What's wrong with a brother investigating his own sister. That is just a normal day in Washington D.C.
Look at the Mueller investigation for example. How many people on his staff are people he knows and has worked with directly or indirectly in the past. He and his whole team were and are a gang of brother all with one singular intent together. And it is not in any way related to such naive ideas like 'truth' or 'justice'.
We have to accept that America has become one of the most corrupt governments on Earth.