Why are dick and Perry's deformities describes in such detail in the book "In Cold Blood"?

I think Capote wanted to give the impression that these Dick, in particular, was isolated by his deformities. Capote writes that Dick's “head had been halved like an apple” making it appear “tilted” and uneven. This gives us the sense that he might have been ostracized by the general public. An immediate reaction by many might be that Dick is sane yet not very bright. The latter of course is not accurate for he is proven to have an IQ of 130. Perry is described as having “chunky, dwarfish legs”. This might explain a similar isolation as Dick. As a result of a motor cycle accident Perry could “never find trousers to fit”. Both men hence remained feeling forever isolated and different.