(PARK CITY, Utah.) — A Utah judge ruled Tuesday that the case of Kouri Richins, the Utah mother accused of murdering her husband with a lethal dose of fentanyl, will go to trial.

The 34-year-old realtor and mother of three, who wrote and self-published a children’s book on grieving following her husband’s death, was arrested last year following a lengthy investigation. She was charged with aggravated murder and drug charges in connection with the 2022 death of her husband, Eric Richins.

Eric Richins, 39, was found dead in the couple’s bedroom on March 4, 2022. An autopsy determined he died from fentanyl intoxication, and the level of fentanyl in his blood was approximately five times the lethal dosage, according to the charging document. The medical examiner determined the fentanyl was “illicit fentanyl,” not medical grade, according to the charging document.

Following a two-day preliminary hearing, Judge Richard Mrazik said Tuesday that the prosecution had shown probable cause for the charges of aggravated murder and distribution of a controlled substance.

He said the prosecution had also shown probable cause that she attempted aggravated murder on Feb. 14, 2022, after the state claimed she gave him a sandwich laced with fentanyl — a first, failed attempt to kill him, prosecutors allege.

Mrazik further said the prosecutors submitted sufficient evidence to support a reasonable belief that Kouri Richins had fraudulently secured a life insurance policy on her husband’s death in January 2022 and “had a significant financial incentive to secure his death because she would do better under the premarital agreement if he were dead and her businesses were highly leveraged,” Mrazik said.

A not guilty plea to all charges was entered on her behalf in court on Tuesday.

Prosecutors have alleged Kouri Richins was having an affair and was deeply in debt when she procured illicit fentanyl and attempted to kill her husband a month before he died by poisoning an egg sandwich on Valentine’s Day. He died by a lethal dose of fentanyl on the night of March 3, 2022, according to the probable cause statement in the charging document.

Prosecutor Brad Bloodworth claimed during probable cause arguments in court on Tuesday that Kouri Richins administered the fatal dose of fentanyl in a “lemon shot” so that Eric Richins would “throw it back all at once.”

“She says that in her journal article,” he said. “She learns that it takes a truckload of fentanyl to kill him. She learns that one bite in the sandwich isn’t enough. It has to be administered at once, and it has to be a lot. And that’s why Eric Richins’ toxicology shows five times the lethal amount in his blood and 20,000 nanograms per millimeter remaining in his gastro fluid.”

Her defense, meanwhile, charged there was no evidence she attempted to poison her husband in either instance.

“You have a claim that Mr. Richins was poisoned on [Feb. 14, 2022]. There is no medical evidence. There is no there is no connection, there is no causation, there is nothing but pure speculation that because they believe she tried to kill him and successfully killed him in March, that that must mean she tried it before,” defense attorney Kathy Nester said.

Kouri Richins was also charged with multiple counts of forgery, insurance fraud and mortgage fraud. Prosecutors allege she forged her husband’s signature on an insurance application weeks before he died. The insurance policy, which became effective 10 days before the alleged Valentine’s Day poisoning, had a death benefit of $100,000, according to the charging document.

During the two-day preliminary hearing, prosecutors presented three witnesses, including a detective on the case who spoke to the alleged drug dealer. A cell mapping expert also testified Kouri Richins texted about 30 times in since-deleted messages with an alleged drug dealer leading up to Valentine’s Day 2022. A financial fraud expert also testified about the defendant’s “increasing” debt load from her home-flipping business.

The defense, meanwhile, seized on the fact that detectives never looked at or interviewed other possible suspects in Eric Richins’ death, that there were no pills found in the family’s home and statements detectives made to the alleged drug dealer, a convicted felon, about working with the prosecutor’s office to reduce charges in exchange for information on Eric Richins’ death.

The defense also claimed the cell mapping expert’s data was unreliable.

Bloodworth said there’s evidence Kouri Richins texted her paramour on Feb. 15, 2022, the day after the alleged Valentine’s Day incident, that “if he could just go away … life would be so perfect.”

“And then two weeks later, she assured her paramour, life is going to be different. I promise, hang in there until Friday,” Bloodworth said. “On Friday, Eric Richards is dead.”

Nester argued the text from Feb. 15, 2022, was not proof of murder.

“I mean, this was not a perfect couple. They didn’t have the perfect relationship. But to take a context, one single text, and to say that that gives you a reasonable belief that she tried to kill him the day before, I don’t see the connection at all,” Nester said.

Kouri Richins waived her right to testify, and the defense did not call any witnesses.

Kouri Richins has remained in jail since her arrest in May 2023. She proclaimed her innocence in an audio recording released in May.

“The world has yet to hear who I really am, what I’ve really done or didn’t do,” Kouri Richins insisted in the audio, provided to ABC News through a trusted confidant. “What I really didn’t do is murder my husband.”

Prior to the preliminary hearing, Kouri Richins was appointed new attorneys by the court after her defense filed a motion in May to withdraw from the case due to an “irreconcilable and nonwaivable situation.”

Her defense at the time had also filed a motion asking the court to disqualify prosecutors for what they alleged was gross misconduct, including the claim the state recorded and listened to privileged calls between Kouri Richins and her attorney.

Prosecutors in a statement called the motion “materially inaccurate” and charged it was “filed in bad faith.”

The judge denied the motion to remove the prosecution earlier this month.

A month prior to her arrest in May 2023, the mom of three appeared on a “Good Things Utah” segment on Salt Lake City ABC affiliate KTVX to promote her book. In the segment, Kouri Richins said her husband of nine years died “unexpectedly” and that his death “completely took us all by shock.”

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