Kessinger said she started seeing the signs on August 13, when Watts texted her saying his family, wife Shan'aan and children Bella, 4, and Celeste, 3, was "gone".
Earlier this month, Watts, 33, pleaded guilty to nine felony counts, including three first-degree murder charges, in the deaths of his wife, Shanann, 34, and two daughters, Bella, 4, and Celeste, 3, prosecutors said.
Now that coworker, Nichol Kessinger, has spoken to the Denver Post about their relationship. They started talking in June and began a physical relationship a few weeks later when Kessinger noticed he hadn't been wearing a ring and found him attractive. "It got to a point that he was telling me so many lies that I eventually told him that I did not want to speak to him again until his family was found".
The Colorado native explained she and Watts, whom she described as "soft-spoken" and "a good listener", had met at work.
The mistress of a Colorado father who admitted to killing his wife and two daughters is telling her story, claiming in a new interview that she had no idea Chris Watts was still married when they were together.
"I believed him", she said.
Nichol Kessinger was having an affair with Watts at the time he murdered his wife and children, but she says she had no idea he was still married.
That same month, Kessinger said he asked her to help him find an apartment for him and his daughters.
While Watts didn't reportedly sound too concerned about their absence, Kessinger became concerned when she saw that the media had taken interest in his wife and children's disappearance.
"When I read the news, I found out he was still married and his wife was 15 weeks pregnant", Kessinger said.
At the end of July, Chris Watts told her that his divorce was final, Kessinger said in the report, which was published online Thursday evening. "He lied about everything". "I was very confused why the media was at his house", she admitted.
Meanwhile, Watts had already made shifty television appearances pleading for his family to return home when they were still reported as missing. But he told police that he strangled her in "a rage" when he discovered she had strangled their two daughters after he sought a separation.
Kessinger said that something seemed "off" about his story.
The bodies of Shan'ann and her daughters were found shortly after, on the grounds of the oil field where Watts and Kessinger worked.