Kouri Richins, the Utah mom and children's book author accused of poisoning her husband to death last year, has sued his estate.

Richins, 33, allegedly killed her husband, 39-year-old Eric Richins, with a fentanyl-laced cocktail the evening of March 3, 2022, at their home in Kamas, just outside of Park City.

The mother of three boys is also accused of purchasing multiple life insurance benefits on Eric's life totaling more than $1.9 million between 2015 and 2017, and changing the beneficiary to herself in January 2022.

"Although Eric and Kouri jointly purchased the Family Home, jointly paid down the mortgage, jointly paid the Utilities, and otherwise agreed and acted in all respects as if the Family Home was a joint marital asset, legal title to the Family Home has remained solely in Eric’s name since its acquisition, with equitable title being held jointly by Kouri and Eric (and subsequently Eric’s trust)," according to Kouri's lawsuit, which was filed against Eric's sister on June 9.

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Kouri and Eric Richins smile together

An obituary for Eric Richins described him as an "avid outdoorsman and dedicated hunter." He enjoyed helping his family's cattle ranch and growing his "successful" masonry business. The obituary also described him as a dedicated family man. (Facebook/Kouri Richins)

Prior to his death, Eric took Kouri off his will and made his sister the beneficiary instead, according to investigators. His family told authorities he had been in fear for his life after Kouri allegedly tried to poison him several years ago in Greece and again on Valentine's Day 2022.

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Eric and Kouri purchased the home from his sister for $400,000 in 2012. They married in the backyard and each contributed to monthly payments on the house.

Eric and Kouri Richins at a football game

Charges filed against Kouri Richins are based on officers' interactions with Richins and an unnamed acquaintance who apparently told authorities that she had sold fentanyl to the mother of three.  (Facebook/Kouri Richins)

Kouri's lawyers say the house is now worth "at least" $1.9 million, and "Kouri is entitled to ½ of all equity in the Family Home," or "at least entitled to ½ of the increase in equity value that occurred after her marriage to Eric."

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"While legal title to the Family Home may have been in Eric’s name, Kouri and Eric both held equitable title," the lawsuit states.

Kouri Richins, a Utah mother of three who authorities say fatally poisoned her husband then wrote a children's book about grieving, looks on during a bail hearing Monday, June 12, 2023, in Park City, Utah.

Kouri Richins, a Utah mother of three who authorities say fatally poisoned her husband then wrote a children's book about grieving, looks on during a bail hearing Monday, June 12, 2023, in Park City, Utah. A judge ruled to keep her in custody for the duration of her trial. (AP Photo/Rick Bowmer, Pool)

The couple was apparently having financial disagreements stemming from Kouri's desire to purchase a $2 million mansion under construction in Wasatch County while Eric thought the home was too expensive. Kouri wanted to flip the mansion and sell it for a profit, a warrant states. 

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On May 4, 2022, the day after her husband's death, Kouri allegedly closed a deal on the Wasatch County mansion "alone," after her husband was pronounced dead.

Kouri and Eric Richins and a mansion

Utah children's book author Kouri Richins had a contentious relationship with her husband, wrought with financial disagreements, before she allegedly killed him with fentanyl. (TownLift, Will Scadden/Facebook)

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After Eric's death, Kouri wrote a children's book about death, "Are You With Me?"

A description for the book, which was listed on Amazon for $14.99, describes "Are You With Me?" as "a must-read for any child who has experienced the pain of loss, and for parents who want to provide their children with the emotional support they need to heal and grow."