Who is Dr. Han Fastolfe from The Caves of Steel and what is their importance?

Dr. Han Fastolfe is a colleague of Dr. Sarton, he has a degree in Sociology, specializing in robotics. He is in charge of the murder investigation on Spacetown's end just as Enderby is in charge on the City's end. Dr. Fastolfe is the first one to really convince Lije there are advantages to colonization and emigration.