NEW YORK — The parents of a Democratic National Committee employee who was killed in 2016 allege Fox News exploited the slaying of their son as a “political football.”Joel and Mary Rich claim in a lawsuit that Fox News, a reporter and a guest commentator used “lies, misrepresentations and half-truths” in a May 16, 2017, article that claimed their son, Seth Rich, had leaked DNC emails to WikiLeaks during the presidential campaign.