Mark Hacking (search) pleaded not guilty Friday to murdering his wife, Lori, whose remains were found in a landfill weeks after her disappearance.

Prosecutors said they would not seek the death penalty against Hacking, whose trial was set for April 18.

Authorities believe Lori Hacking (search), 27, was killed July 19 after learning her husband had not been accepted to medical school in North Carolina, as he had claimed. The couple were packing to move there when she vanished.

The innocent plea infuriated the victim's family.

"I know that one day Mark will receive perfect judgment from the only judge who knows every detail of what he did that terrible night," Lori Hacking's mother, Thelma Soares, said outside court.

Prosecutor Robert Stott said he was not seeking the death penalty because he cannot prove Lori Hacking was five weeks pregnant, as she told friends. Her remains were badly decomposed. Utah law allows the death penalty for multiple murder.

Hacking's attorney indicated he would challenge Hacking's alleged confession to his brothers that he shot his wife in the head while she slept and disposed of her remains, the weapon and a mattress in trash bins.

"Any time they call a family member to testify against another family member, it's going to be painful," said Scott Hacking, a physician who said his brother underwent extensive psychiatric testing while in jail.

Hacking's plea came after the victim's brother, Paul Soares, begged him in a letter to "save your family the grief and cost" and plead guilty to murder.