Just weeks before he murdered his whole family, Chris Watts warned "big things will happen this year" in a handwritten note.
In romantic cards and notes address to his mistress Nicole Kessinger, the killer dad left dark and ominous clues.
Friends and family never realised the picture perfect Watts could become the ruthless and sadistic "killer dad" he is known as today, news.com.au reports.
Watts murdered his wife and children before submerging the bodies of his young daughters in oil drums on an old work site and burying his wife in a shallow grave.
As authorities struggle to find clues to what led Watts to do the unthinkable, the Weld County District Attorney's office has provided new documents to news.com.au including love letters sent by Watts to his mistress Nichol Kessinger.
In the handwritten notes on hot pink cards and yellow paper, he left an ominous clue for what was to come among the effusive and sexually charged praise for his mistress.
At the top of one card Watts had written the lyrics: "Your energy is so insane, you heat me up then cool me down like rain," from a song by Through the Roots called Take You There.
Watts ominously warns Kessinger in his scrawled notes that "big things will happen this year."
"BIG THINGS WILL HAPPEN THIS YEAR"
It's clear now that Watts' plan was to leave his wife and family and take up permanently with Kessinger. She has been cooperative with police and informed on Watts when she clocked that he seemed unperturbed at his wife's disappearance.
As they began their affair, Watts mislead Kessinger about the nature of his marriage, telling her he was in the final stages of a divorce. He boldly brought her to his home on two occasions while his wife was not at home.
Watts had been having an affair for some months and planned to spend his life with his mistress. It is believed he killed his wife and two young daughters to clear the path for the pair to be together.
One card also read, "That smile (that stare), that laugh (that giggle) gets me every time!!"
KILLER DAD OBSESSED ABOUT MISTRESSES "ELECTRIC" ENERGY
Another card dated from later in the month is addressed to "Nikki" in one corner, with "Love Chris" in the far right corner.
Scrawled in-between are a number of sexually charged lyrics: "You keep my engine roaring when your (SIC) pushing on the pedal," Watts wrote.
The last of these notes was dated at the end of July and it was delivered just weeks before Watts would strangle his wife and smother his daughters to death.
Another letter from Watts to his former lover gives detail into their romance.
Watts repeatedly refers to her as "electric" and uses metaphors about "energy" and to describe the relationship.
"The first day I had the guts to talk to you, I got lost in those stunning green eyes," Watts wrote to his mistress.
"The first time we hung out in the park together, I knew I was addicted."
The pair met at work and Kessinger described the relationship as mostly sexual in nature, saying they spent most of their time together in her home, occasionally going out. They bonded over an interest in healthy food.
"We have a lot of FIRSTS together Nikki. And I want keep having them with you!!"
Watts texted Kessinger shortly after he killed his two daughters Bella, four, and Celeste, three, and his wife Shannan 34.
At 3.45 in the afternoon she received the first in what would be a dozen texts that day, a message simply telling her that his family had "gone".
As journalists began to swarm around a strangely calm Watts' house, Kessinger became alarmed to discover his wife was 15 weeks pregnant.
Watts stood on his family's porch and explained to a reporter on camera how it was extremely unusual for his wife not to be home. His speech appears pressured, but he is lucid and calm. The footage was disturbing.
"I have no idea, like, where they went. I don't feel like this is even real right now. It's like a nightmare I can't wake up from," he said outside him home before being arrested for the killings.
MISTRESS: "HE'S A LIAR."
"He's a liar. He lied about everything," Kessinger told a reporter after two years of silence.
Kessinger became suspicious of police when she discovered Watts had lied to her about his wife being pregnant.
"I thought, 'If he was able to lie to me and hide something that big, what else was he lying about'?"
"I just wanted to help … with a pregnant woman and two children missing, I was going to do anything that I could," she said.
Watts pleaded guilty to his charges of murder in the first degree, three counts of tampering with a deceased human body and one count of unlawful termination of a pregnancy on the 6th of November this year.
WATTS AND HIS SLAIN WIFE HAD NAMED UNBORN CHILD
Watts' and Shannan had spoken about the name of their unborn child.
"Little Peanut! Love her/him already!!!" he replied to her, when she sent him a an ultrasound photo of their child in her stomach.
Sharing the exchange on her Facebook page, she wrote, "I love Chris! He's the best dad us girls could ask for."
They had planned to call the unborn child Niko.
Back in April Shannan, who regularly shared loving posts about her husband, posted "He's my rock!" while she was out of town on a work trip.
"He takes care of us girls unconditionally! Thank you baby for holding down the fort this weekend! Love you," she wrote.
The couple met when Watts sent her a friend request on Facebook. "I accept, one thing led to another and eight years later we have two kids, we live in Colorado and he's the best thing that has ever happened to me," she wrote, explaining how the man who would eventually murder her and her children came into her life.
"Because of my health challenges I let him in … he knew me at my worst and he accepted me. Through sickness and everything he's been there," he said. "When I met Chris I pushed him away, I gave every excuse for him to run, I gave him an out every single day … I tortured him, I pushed him away … But he stuck around because he was the one for me, I can't tell you how wonderful he is."
the family filed for bankruptcy in 2015, but Shannan had recently landed a new job that paid $80,000 a year.
Watts escaped the death penalty for his guilty plea, but will serve life in prison.