Complex sentence: It would seem to be an open-and-shut case, suicide brought on by depression, but Bannion is then contacted by the late cop's mistress, Lucy Chapman (Dorothy Green), who claims that it could not have been suicide.
Split into simpler sentences: It would seem to be an open-and-shut case, suicide brought on by depression. However, Bannion is then contacted by the late cop's mistress, Lucy Chapman (Dorothy Green), who claims that it could not have been suicide.