Meijer (in this chapter) is referred to both as "Professor Inspector Meijer" and as "professor-inspector Meijer"['s TED talk]. I think the hyphenated phrase "professor-inspector" is the correct usage. The question is, is "professor-inspector" Meijer's actual job title, or merely his profession? If it's his job title then he should consistently be referred to as "Professor-Inspector Meijer". If it's just his profession then you need to consistently use the phrase "professor-inspector" throughout the book.