SALT LAKE CITY, March 18 — A Utah woman who poisoned her husband with a fatal dose of fentanyl — before publishing a children’s book about grief — has been convicted of aggravated murder.

According to US media reports, Kouri Richins was found guilty on Monday of killing her husband, Eric Richins, after prosecutors said she slipped five times the lethal dose of the powerful synthetic opioid into a cocktail he drank in March 2022.

The chilling motive laid out in court painted a picture of greed and betrayal. Prosecutors said Richins was drowning in US$4.5 million (RM17.6 million) of debt and believed she stood to inherit more than US$4 million upon her husband’s death. At the same time, she was allegedly planning a future with another man.

“She wanted to leave Eric Richins but did not want to leave his money,” Summit County prosecutor Brad Bloodworth told the court.

The jury needed less than three hours to reach a verdict. As it was read out, Richins reportedly stared at the floor, taking deep breaths, while family members from both sides embraced and wept.

The case took an even darker turn as jurors also convicted her of attempted murder, after prosecutors said she had tried to poison her husband weeks earlier on Valentine’s Day with a fentanyl-laced sandwich that caused him to black out. She was also found guilty of forgery and fraudulently claiming insurance benefits following his death.

Investigators told the court that Richins, a real estate agent who flipped houses, had secretly taken out multiple life insurance policies on her husband worth about US$2 million.

Jurors were shown text messages between Richins and a man she was allegedly seeing, in which she fantasised about leaving her husband, gaining millions and marrying her lover.

Her internet search history added to the prosecution’s case, including queries such as “what is a lethal.dose.of.fetanayl”, “luxury prisons for the rich America” and “if someone is poisned (sic) what does it go down on the death certificate as”, a digital forensic analyst testified.

In a dramatic moment, prosecutors replayed Richins’ 911 call from the night her husband died. Bloodworth told jurors it was not the grief-stricken panic the defence had described.

“That’s not ‘the sound of a wife becoming a widow’,” he said. “It’s the sound of a wife becoming a black widow.”

The trial, initially expected to last five weeks, ended abruptly after Richins waived her right to testify and her legal team rested without calling any witnesses. Her lawyers had argued that prosecutors failed to produce enough evidence to prove murder.

For Eric Richins’ family, the verdict brought a measure of closure.

“Honestly I feel like we’re all in shock,” his sister, Amy Richins, said. “We got justice for my brother.”

Richins is due to be sentenced on May 13 — the day her husband would have turned 44. The aggravated murder conviction alone carries a sentence of 25 years to life in prison.