what is the role of Mr Utterson in Dr Jekyll and Mr. Hyde novel

The narrator of the book, Utterson is a middle-aged lawyer, and a man in which all the characters confide throughout the novel. As an old friend of Jekyll, he recognizes the changes and strange occurrences of Jekyll and Hyde, and resolves to further investigate the relationship between the two men. He is perhaps the most circumspect, respected, and rational character in the book, and it is therefore significant that we view Hyde's crimes and Jekyll's hypocrisy through his observant, but generally sympathetic perspective.