Utah authorities on Monday arrested Kouri Richins, a mother of three and the author of a children's book about grief, in her husband's fentanyl death.

Prosecutors say Richins, 33, poisoned her husband, Eric Richins, 39, with fentanyl last year at their home in Kamas, just outside of Park City, while their three young sons were sleeping.

"Life is just so damn hard without you here!" Richins recently captioned a May 4 video with photos of her family posted to Facebook. "The cards I have been dealt just seems like a game that can't be played."

Kouri Richins called 911 on the evening of March 3, 2022, to report her husband was "cold to the touch."

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Kouri and Eric Richins smile together

Prosecutors in Utah are accusing Kouri Richins, 33, of poisoning her husband, Eric Richins, 39, with fentanyl last year at their home in Kamas, outside of Park City, while their sons were sleeping. (Facebook / Kouri Richins)

She told authorities at the time that she had served her husband of nine years a cocktail in bed to celebrate a home sale for Kouri Richin's business that evening, according to a warrant.

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She said she left him briefly to check on one of her three sleeping children, and when she returned, she found Eric Richins unresponsive, according to a warrant.

Kouri Richins, Eric Richins and their three sons

Eric Richins had five times the lethal dosage of fentanyl – an opioid that is already about 50 to 100 times more potent than morphon – in his blood. (Facebook / Kouri Richins)

Eric Richins had five times the lethal dosage of illict fentanyl – an opioid that is already 50 to 100 times more potent than morphine – in his blood, according to the medical examiner.

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Kouri Richins is also facing charges of possession of GHB, commonly known as the "date rape drug."

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Her charges are based on officers' interactions with Richins and an unnamed acquaintance who apparently told Summit County authorities that she sold fentanyl to the mother of three, who had asked for "some of the Michael Jackson stuff," the warrant states.

Authorities said they determined during their investigation that despite Richins' statements saying she left her phone in her bedroom when she went to check on her children the night of March 3, 2022, her phone activity indicated that it had been locked and unlocked multiple times during that period and showed no physical movement.

Additionally, messages were sent and received during that period but deleted, investigators said.

Eric and Kouri Richins at a football game

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

Richins' arrest also comes two months after she appeared on TV to promote her children's book about grief, "Are You With Me?"

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A description for the book, which sells for $14.99 on Amazon, states that "Are You With Me?" is "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."

Kouri Richins headshot

Kouri Richins is shown at the KPCW studio in Park City, Utah, on April 12, 2023. (KPCW.org via AP)

Richins told "Good Things Utah" the book is about explaining to her children that just because their father is "not present here with us physically," that "doesn't mean his presence isn't here with us."

On March 19, Richins shared a link to her book in a Facebook group called "grieving mothers," writing, "I lost my husband unexpectedly last year and we have 3 amazing young boys! As I was trying to find books that would help comfort them at nights, I really couldn’t find anything! So I wrote my own and it just came out this week on Amazon."

Kouri and Eric Richins smile together

An obituary for Eric Richins describes 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 describes him as a dedicated family man. (Facebook / Kouri Richins)

An obituary for Eric Richins describes 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 describes him as a dedicated family man.

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"Eric did absolutely everything in his power to provide his family with every possible opportunity to learn, grow, and have fun," his family wrote.

The Associated Press contributed to this report.