A woman who wrote a children's book about dealing with grief following her husband's death has been charged with his murder. 

Kouri Richins was arrested on Monday in Utah and is accused of poisoning him with fentanyl.

Prosecutors say five times the lethal dose was found in Eric Richins' system after he died in March 2022 at their home in Kamas, near Park City.

She allegedly told police she'd made a mixed vodka drink to celebrate him selling a house - but later found him "cold to the touch" after returning from checking on one of their children.

The charges come after an "unnamed acquaintance" is said to have admitted selling her the fentanyl - a painkiller 100 times more potent than morphine.

She is also charged with allegedly possessing GHB, an odourless substance often associated with 'date rape' cases due to its ability to make people drowsy or relaxed.

Two months ago, Richins promoted her grief book on local TV.

She told a segment called 'Good Things Utah' she'd written it to help the family deal with her husband's death.

Richins said children needed to feel that a loved one's "spirit is always alive in your home".

| Pic: Amazon

"It's - you know - explaining to my kid just because he's not present here with us physically, doesn't mean his presence isn't here with us," she told the programme.

Her lawyer, Skye Lazaro, declined to comment on the charges.