Rep. Katie Hill, the subject of a new House Ethics Committee inquiry over an alleged relationship with a staff member, is the first female lawmaker to face such a charge.

The first-term California Democrat denies she ever had an inappropriate relationship with her legislative director, Graham Kelly, as alleged by her estranged husband, Kenny Heslep. The pair are in the midst of divorce proceedings, and Heslep also alleged that he, Hill, and a staff member on her successful 2018 campaign for a northern Los Angeles County seat were engaged in an intimate relationship, including explicit photos that appeared on the conservative site RedState.

Hill admitted Wednesday night to having an affair with a campaign worker and promised to work with the House Ethics Committee.

Dozens of House members have been involved in Capitol Hill sex scandals, but to date, they've all been men. Members of both parties have been implicated.

In 2017, for instance, then-Rep. Trent Franks, an Arizona Republican, was investigated by the ethics committee after House officials learned that he had asked two female employees to bear his child as a surrogate. But Franks abruptly resigned before the committee study concluded, meaning the panel lost jurisdiction since he was no longer a House member.

In 2010, first-term Rep. Eric Massa, a New York Democrat, resigned to avoid an ethics investigation into his admitted groping and tickling of multiple male staffers.

Congressional sex scandals in earlier decades occurred when the House had overwhelmingly male membership.

Relationships between members of Congress and campaign staff are not plainly addressed in the House code of conduct. Including Hill, there are currently 102 women serving in the 435-member House, about 23%.

And while relationships between House members and their aides clearly fall under the House Ethics Committee's jurisdiction, particularly after the chamber beefed up its rules in recent years due to #MeToo scandals, questionable behavior during a congressional campaign is a murkier area.

On Dec. 1, 2017, a former campaign staffer accused first-term Nevada Democratic Rep. Ruben Kihuen of sexual misconduct. By Dec. 17, 2017, the House Ethics Committee launched an investigation into Kihuen. He ended up serving a single term in the House. Shortly before Kihuen left office, in November 2018, the ethics committee formally sanctioned him, determining he "made persistent and unwanted advances towards women."

The alleged relationship between Hill and her female campaign staffer has been assumed to be consensual, but, according to new text messages released on Tuesday by RedState between the staffer and Hill’s estranged husband Heslep, as well as Hill herself, the three-way relationship was described as “dark” and “toxic” by the young female staffer.

In one text message, the staffer described her discomfort with Hill when she asked her to put sunscreen on her before a campaign event.

“Hi. I did my very best to be professional and keep things normal at [work]. I would really appreciate it if you didn’t ask me to do things like put sunscreen on you,” the staffer said.

Hill replied, “You did a great job. And I was not trying to ask you. I was trying to get one of the others to. But you were standing right there and they kinda turned to you and I didn’t know what to do.”

Democrats refuse to go on the record about Hill’s situation, waiting to see how it plays out. But one male House Democrat who faced the ethics committee in the past told the Washington Examiner that despite her gender, "she is likely to be treated like anybody else and will go through Ethics."

When asked if men and women who find themselves in congressional scandals are treated differently, the member replied, "I smiled [when I first heard about Hill’s story] because it showed we have come full turn, because now women are [facing the same scrutiny] that men here are."

Another male Democratic House member told the Washington Examiner, “I don't think that [Hill] will be treated unfairly. She needs to be treated fairly, and you can't jump to any conclusions, just like if it was anybody else, man or woman. We just need to drive out and focus on any unethical behavior."