In the third installment of CNBC Make It's new series HR Confidential, a New York-based human resources professional with nearly five years of experience tells Ruth Umoh about a violent confrontation when an employee referred to a transgender co-worker by the wrong pronoun. The below is told in the HR pro's own words, and has been edited for length and clarity.

The scenario:

I was working in corporate HR for a retail company that had a bunch of small boutique stores. One of those stores employed a transgender woman who asked to be referred to as "she" and "her." In that same store, there was a co-worker who could not seem to comprehend that the transgender employee wanted to be called by those preferred gender pronouns. The co-worker kept slipping up and referring to the woman as "him" and "he." This happened consistently for many weeks and the transgender woman was becoming very upset. One Friday evening, the co-worker once again referred to the transgender employee with the incorrect gender pronoun. At the time, the transgender woman happened to be slicing soap so there was a knife in her hand. She just lost it. The transgender employee clenched the knife, lifted it up to the co-worker and threatened her, saying she was going to kill her for calling her the wrong pronoun.

I requested that both employees be sent home through the weekend. Anonymous HR manager

The co-worker immediately reached for a phone and called the cops. The police were initially going to arrest the transgender employee but the co-worker decided not to press charges. She did, however, obtain a restraining order against the transgender woman. I received a call about this incident late Friday evening. Because I observe Shabbat, my phone was turned off. When I finally heard what happened later that night, I panicked. I requested that both employees be sent home through the weekend, which gave me time to get all the information that I could from the police. Over the next two days, I began to unravel the situation and figure out what had happened. Luckily, the death threat occurred around 6 p.m. when there weren't any customers in the store. However, there had been prior incidents during which the two employees had engaged in full-blown arguments with customers present.

The solution:

We brought the transgender woman into the corporate office on Monday to hear her side of the story. She talked about how difficult her life is: She'd been disowned by her family, left out on the streets and had to do horrific things just to make money and stay alive.

Mistakes do happen. Anonymous HR manager

She told us that this altercation stems from the pain that she's been through and that the reason she's so defensive is because she has so much pent-up anger. She also said it's unfair that she felt unsafe in her workplace and that she shouldn't have to defend her job and identity. Despite all of these sensitivities and after hearing her rationale, we just had to let her go. At the end of the day, she threatened another employee with a knife.

The lesson:

The main question for us was, 'Well, if there's a restraining order and they both work for the company, what's our responsibility?' Coupled with the physical altercation, we told the transgender employee that we, unfortunately, could not continue to employ her. However, what we tried to explain to her is that we hear her personal story, we don't judge her for her personal story and we think that she has every right to be upset. But the main issue was how she dealt with the problem when she became upset. For that, we had to let her go. We also spoke with the co-worker whose life was threatened. She told us that she didn't mean to be ignorant, for lack of a better word. She said she was an open-minded person but she just wasn't familiar with the transgender community.