This was a killer. Quite possibly a soldier, though Lilo was not expert in mental diseases. John Varley
The book was Maniacs in the Fourth Dimension, by Kilgore Trout. It was about people whose mental diseases couldn't be treated because the causes of the diseases were all in the fourth dimension, and three-dimensional Earthling doctors couldn't see those causes at all, or even imagine them. Kurt Vonnegut