If you include author: in your query, Google will restrict your Google Groups results to include newsgroup articles by the author you specify. The author can be a full or partial name or email address. For example, [ children author:john author:doe ] or [ children author:doe@someaddress.com ] return articles that contain the word "children" written by John Doe or doe@someaddress.com.

Google will search for exactly what you specify. If your query contains [ author: "John Doe" ] (with quotes), Google won't find articles where the author is specified as "Doe, John."