Walsh’s allegation is potentially the most explosive of all: Fox News was apparently unaware of it until she raised it for the first time in an interview with the New York Times this month. Her complaint has triggered an investigation at Fox by the law firm Paul, Weiss, Rifkind, Wharton & Garrison, the same firm that uncovered widespread harassment allegations against Fox News chairman Roger Ailes last summer, leading to his ouster. A similar fate could await O’Reilly; a negative finding by the law firm could force the hands of Fox News Chairman Rupert Murdoch and his sons, James and Lachlan, who run Fox’s parent company…

According to Walsh, 54, O’Reilly dropped her as a regular guest on his show and reneged on a promise to help her secure a paying position as a Fox News commentator after she turned down his invitation to visit his hotel suite during a dinner meeting in Los Angeles in February 2013.

However, O’Reilly’s defenders say O’Reilly never made a job offer and did not retaliate against her. Instead, they say, O’Reilly was continuously helpful to Walsh after their meeting at the Hotel Bel-Air.

O’Reilly, for example, continued to invite her on his program for four months after the hotel encounter. During several of her appearances, which focused on relationships and behaviorial issues, O’Reilly plugged Walsh’s book, “The 30-Day Love Detox,” a valuable bit of promotion, given O’Reilly’s large audience.