FARMINGTON, Utah — A Utah judge on Thursday ruled there's enough evidence for a man accused of killing his 4-year-old stepson to stand trial on murder charges.

Prosecutors say 34-year-old Nathanael Sloop and his wife malnourished and abused the boy for days until he died in May 2010. Sloop is accused of using a hammer to disfigure Ethan Stacy's face and burying his body in the northern Utah mountains.

The Salt Lake Tribune reports (http://bit.ly/145OCIm) Second District Judge Glen Dawson on Thursday ordered Sloop to stand trial on charges of aggravated murder, child abuse, obstruction of justice and desecration of a body. Prosecutors say they plan to seek the death penalty against Sloop.

Sloop's defense attorneys are challenging the law which prosecutors are using to seek the death penalty. The law allows prosecutors to pursue capital punishment in a killing that resulted from child abuse, kidnapping or sexual assault. Prosecutors do not have to prove the killing was intentional — only a "reckless indifference to human life."

Defense attorney Richard Mauro said Thursday that the law is unclear and poorly written.

Prosecutors argue it's too soon in the process to argue the law, and Dawson agreed on Thursday, declining to rule on the matter for now.

Sloop is due back in court on Aug. 13 for an arraignment.

He pleaded guilty to the charges last year, but later invoked his right for a judge to hear testimony and evidence to determine whether there was probable cause for a trial. Sloop had initially waived that right, but changed course late last year after prosecutors declared they were seeking the death penalty.

Dawson's ruling on Thursday now sends Sloop back to once again enter a plea to the charges.

His wife, Stephanie Sloop, is also accused of contributing to her son's death and is awaiting trial.

During four days of preliminary hearings this spring, a medical examiner testified that Ethan died from a combination of too many over-the-counter medications, pneumonia and severe burns.

Dr. Edward Leis said the burns were likely from hot water in a bathtub.

A burn specialist testified that the injuries would have left the boy dehydrated and nauseous and caused his skin to blister and fall off. The burns would have required skin grafts and weeks of hospitalization. Dr. Jeffrey Saffle said.

The boy died only 10 days after he arrived in Utah from his birth father's home across the country. The boy's father, Joe G. Stacy, of Tazewell, Va., said he was forced to give up Ethan during the summers as part of a divorce and custody agreement.