FESSENDEN (AP) - A woman accused of helping her fiance kill a Wells County couple whose bodies were found in their burned out home has been ordered to stand trial.

Tamara Sorenson, of Fargo, pleaded not guilty on Tuesday to charges that she was an accomplice in the April slayings of Donald Willey, 70, and his wife, Alice, 67, of rural Sykeston.

Authorities said the Willeys were shot and their home was set on fire. They were found dead in their home April 7.

Judge James Bekken on Tuesday ruled there was enough evidence for Sorenson to stand trial.

Wells County State's Attorney Kathleen Trosen has filed a motion to join the trials of Sorenson and her fiancé, Aron Nichols. The prosecutor said the two schemed together to kill the Willeys.

Nichols has pleaded not guilty to murder charges.

Court records show Sorenson and Nichols battled with the Willeys over visitation rights to Sorenson's daughter, who was the daughter of the Willeys' late son, Andrew.

Attorneys for Nichols and Sorenson, both 29, want to keep the cases separate, arguing that it is too late to join them and could lead to guilt by association.

Trosen said in court documents that Sorenson and Nichols "made direct or overt statements to third parties about killing" the Willeys and worked together in the "planning, preparation and execution of the murder plot."

The prosecutor said Sorenson gave Nichols a hand-drawn floor plan of the Willey home and cited calls between them.

Investigators recovered .45-caliber bullets from the scene and their remains, which testing matched to marks on a shell casing found at the couple's Fargo home. Authorities also found instructions on how fires burn and jars with gasoline-soaked mothballs.

Sorenson's attorney, David Ogren, said it is unclear whether Sorensen knew the items were in her home. He also said it is common for an engaged couple to talk on the phone.

Nichols' attorney argued that prosecutors missed their opportunity to charge the two together when they filed charges against Sorenson two months after charging Nichols.

He is being held on $1 million bail. Sorenson is being held on $750,000 cash bail.