Image copyright Courtesy Fargo Police Department Image caption Savanna LaFontaine-Greywind, was found dead in Red River

A couple in North Dakota are facing murder charges over allegations they killed a pregnant woman to claim her baby as their own.

Savanna LaFontaine-Greywind, 22, was eight months pregnant when she went missing on 19 August.

Her body was found by kayakers in Red River on Sunday, wrapped in plastic and trapped by a log, the Minneapolis Star Tribune reported.

Her death has been preliminarily ruled a homicide, according to Fargo police.

Thirty-two-year-old William Hoehn and 38-year-old Brooke Crews are in custody.

They have told police differing accounts of how they came to be caring for a healthy two-day-old newborn after Ms LaFontaine-Greywind visited their apartment on the day she went missing.

The discovery of her body brings an end to the eight-day-long search for the expectant mother and nursing assistant, which included hundreds of volunteers, search dogs, and local, state and federal law enforcement officers.

Police presume the baby is Ms LaFontaine-Greywind's daughter, but DNA test results are pending.

Ms Crews and Mr Hoehn face further charges of kidnapping and lying to investigators.

Image copyright Courtesy Fargo Police Department Image caption Brooke Crews

Image copyright Courtesy Fargo Police Department Image caption William Hoehn

In interviews with the police, Ms Crews said she invited Ms LaFontaine-Greywind to her upstairs apartment and told her how to induce childbirth.

Two days later, Ms Crews claimed, Ms LaFontaine-Greywind returned to the apartment and handed her a baby.

According to the police affidavit, she "admitted she had taken advantage of Savanna Greywind in an attempt to obtain her child and possibly keep the child as her own".

During three preliminary searches of the apartment, the Fargo Police Department found no evidence of criminal activity.

Image copyright Courtesy Fargo Police Department Image caption Fargo police released photos of this vehicle, believed to be involved in LaFontaine-Greywind's disappearance

But on 24 August, police executed a search warrant on the apartment and discovered the newborn baby.

In subsequent police interviews the couple gave conflicting stories about what happened.

According to court documents, Mr Hoehn claimed he came home from work to find Ms Crews cleaning up blood in the bathroom, and showed him the baby.

"This is our baby, this is our family," he claimed Ms Crews told him.

He admitted disposing of bloody towels and shoes in a dumpster across town.

The results of a preliminary autopsy released on Tuesday found Ms LaFontaine-Greywind's cause of death to be "homicidal violence" but did not contain details of how her baby was delivered.

An abandoned farm in nearby Moorhead, Minnesota, is now an active crime scene in connection with Ms LaFontaine-Greywind's death. Both Mr Hoehn and Ms Crews are being held on a $2m (£1.5m) cash bond.

Ashton Matheny, Ms LaFontaine-Greywind's boyfriend and the father of the baby, complained that he has not been allowed to see her pending DNA results.

"They're admitting it's [our] baby. I guarantee if I saw it I could tell whose child is," he told the St Paul Pioneer Press.

"My world's gone, man. They took my world from me."

He said he named the infant Haisley Jo.