New details emerge about the alleged search history of the Utah mom charged with her husband's murder

A judge denied the pretrial release of Kouri Richins - a Utah widow accused of killing her husband before she authored a children's book about grief - saying she must remain in custody pending the outcome of her trial due to the "substantial evidence" against her.

The judge's decision to deny bail came as new details about the widow's alleged search history emerged as part of the case against the 33 year old, who appeared in a Park City, Utah, court on Monday.

"What is a lethal dose of fentanyl" was one of many phone searches that investigators say were made by Kouri Richins. Prosecutors allege she killed Eric Richins, her husband of nine years, with a lethal dose of fentanyl. She faces charges of criminal homicide, aggravated murder and three counts of possession of a controlled substance with intent to distribute. She has not yet entered a plea.

In court Monday, Judge Richard E. Mrazik ruled Kouri Richins to be held without bail and cited the severity of the punishment of aggravated murder and the "uniquely dangerous nature of fentanyl."

"The circumstances of this case weigh soundly against granting pre-trial release of any kind," Mrazik said, adding the array of possible penalties in a murder case "creates a powerful incentive for a defendant to resort to desperate acts that might include harming themselves, harming the members of their family or harming witnesses in the case."

During the hearing, prosecutors called on several expert witnesses to testify about the investigation into Kouri Richins' phone records and financial history. The defense did not call any witnesses.

Her attorney, Skye Lazaro, argued there was not adequate evidence proving she had purchased fentanyl and disputed that Kouri Richins' financial troubles were a motive for her to kill her husband.