The Guilty Ones — Ross MacDonald

Lew Archer didn't like his client, J. Reginald Harlan, M.A. Of course Archer generally didn't like people whose names started with a single syllable. Harlan hired Lew to find his sister. A respectable school mistress that has run off with a bohemian artist type. But he finds more than what he expected when he has a corpse literally dumped on him!