A woman wrote a children's book about grief after her husband died. Now she is charged with his murder.

 A widow who wrote a grief book for children after her husband died last year is now charged with his murder.

Kouri Darden Richins was arrested in Park City, Utah, Monday on charges including felony first-degree aggravated murder stemming from the early 2022 death of her husband Eric Richins, according to charging documents in the criminal case.

Local officials said the 33-year-old author poisoned her late spouse with a lethal dose of fentanyl at their home in Kamas, a small mountain town in Summit County.

Court documents obtained Tuesday by USA TODAY show an investigation into his death began March 4, 2022 when Summitt County Sheriff's Office deputies responded to her home just after 3 a.m. for a report of an unresponsive man.

According to Kouri Richins' arrest warrant, arriving deputies found her husband dead on the floor at the foot of his bed.

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During interviews with Kouri Richins, she told deputies the couple was celebrating closing on a home purchase for her business the night before.

"Defendant stated that she made Eric a Moscow Mule in the kitchen and brought it to their bedroom where Eric consumed it while sitting in bed," the warrant reads.

The only people in the house, deputies wrote, were the couple and their children. The warrant goes on to state Kouri Richins said she slept with one of her children in the child’s bedroom because the child was scared.

She told authorities she awoke about 3 a.m., returned to the couple's bedroom, felt that Eric was cold and dialed 911.

"Defendant told law enforcement that when she left her room to go to her child’s room, she left her phone plugged in next to her bed and did not take it to her child’s room," the warrant continues.

"However, between when the defendant said she went to child’s room and when she called 911, the status on her phone shows that it was locked and unlocked multiple times and there was also movement recorded on the phone."

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Five times the lethal dosage

According to the warrant, autopsy and toxicology findings show the victim died from fentanyl overdose. A medical examiner found the level of fentanyl in his system was nearly five times the lethal dosage.

The coroner also said the fentanyl was illicit and ingested orally.

In addition to murder, Kouri Richins also faces three other charges including possession of GHB, a narcolepsy drug sometimes used in recreational settings including dance clubs.

Richins released children's book: 'Are you with me?'

The charges, based on officers' interactions with Kouri Richins that night and the account of an “unnamed acquaintance” who claims to have sold her the fentanyl, come two months after Richins appeared on local television to promote “Are you with me?” a picture book she wrote to help children cope after the death of a loved one.

A link to the book's listing on Amazon appeared to have been taken down by Tuesday.

Richins' Salt Lake City based attorney, Skye Lazaro, could not immediately be reached for comment by USA TODAY.

Her client is due in court for a detention hearing on the case next week, court records show.

Contributing: The Associated Press.

Natalie Neysa Alund covers breaking and trending news for USA TODAY. Reach her at nalund@usatoday.com and follow her on Twitter @nataliealund.