High-Pitched Killers

You, the author, are clearly not very bright. You made a 'joke' that relies on the double meaning of 'high-pitched'. The joke is funny because 'high-pitched' can describe the sound a person makes, but it's also a way of describing how a person is when they are very high. The implication here is that child murderers are always literally high or figuratively elevated by the awful things that they do. It's messed up and that's why it's funny.