A 22-year-old pregnant woman, who disappeared from her Fargo apartment earlier this month, died from homicidal violence, authorities said Tuesday.

Savanna LaFontaine-Greywind's body was found in the Red River on Sunday after she disappeared Aug. 19 from the apartment she shared with her parents.

A couple who lived upstairs, William Hoehn, 32, and Brooke Crews, 38, were charged Monday with conspiring to kidnap and murder LaFontaine-Greywind and steal her baby, who remains in protective custody, to claim as their own.

Fargo Police announced the preliminary cause of death on Tuesday, but the full autopsy report from the Ramsey County medical examiner's office isn't expected for weeks while Minnesota and North Dakota investigators continue to work the case. LaFontaine-Greywind was eight months pregnant at the time of her death.

The crime has shocked the Fargo-Moorhead area and total strangers from across the country. Messages have poured in on social media with offers to donate money, baby clothes or other items to her family. From St. Paul to Grand Forks, people are gathering in prayer to honor LaFontaine-Greywind, while other vigils are taking place throughout the region — from Winnipeg to her hometown of Belcourt, N.D.

"It's been hard for the community — not only the native community, but the whole community," said Willard Yellow Bird Jr., Fargo's cultural planner who is also a liaison to the city's Native American Commission, the first of its kind in the U.S. "It never happens in our town."

About 100 people, most of them dressed in Savanna's favorite color, green, prayed outside the Ramsey County medical examiner's office in St. Paul Tuesday night.

Before the prayer circle began, the group marched several blocks on University Avenue to the medical examiner's office with large cloth posters: "Justice for Savanna" and "#MMIW [Missing and murdered indigenous women] No More Stolen Sisters."

LaFontaine-Greywind was a member of the Spirit Lake Dakota tribe, and her death has devastated the broader American Indian community, Yellow Bird said, drawing hundreds of tribal members from across the Midwest to help with searches and support the family.

"It's hard for me to believe that she went through such a brutal ordeal," added Tarita Silk, an aunt who lives in Spearfish, S.D. "We need to have some closure. We want to know what happened."

Silk described LaFontaine-Greywind as a gentle spirit, a true "girly-girl" who enjoyed getting dolled up with makeup and listening to music. She worked as a certified nursing assistant at a West Fargo senior center and was excited about the birth of her baby girl, Haisley Jo, whose due date was Sept. 20.

"Getting so close," she wrote online on Aug. 13 with a heart emoji.

Six days later, she told her family she was going upstairs to a neighbor's apartment to model a dress.

Hoehn told investigators he returned home that day to find Crews, his girlfriend of three years, cleaning up blood in their bathroom, according to documents filed Monday in Cass County District Court. He said she then showed him a newborn baby girl.

"This is our baby, this is our family," she told him.

Conflicting accounts

Crews gave police a different account.

According to the criminal complaint, she told investigators that she called LaFontaine-Greywind to her apartment Aug. 19 and instructed her on how to self-induce birth by breaking her own water. She said LaFontaine-Greywind left, and returned two days later to give Crews the baby.

Police arrested Crews and Hoehn last Thursday. Hoehn admitted to police that he removed garbage bags with bloody towels and his own bloody shoes from the apartment and disposed of them.

Authorities found the newborn on their fourth search of the apartment. The girl, who remains in the custody of Cass County Social Services, is believed to be LaFontaine-Greywind's, but authorities are doing DNA tests to be sure.

Police haven't said whether LaFontaine-Greywind's body showed evidence of a Caesarean section or of labor having been induced. It's also unclear where she died.

After an eight-day search, LaFontaine-Greywind's body was found by kayakers.

Her boyfriend and the baby's father, Ashton Matheny, told Fargo TV station WDAY that "my world's gone," adding that the couple of six years was going to move in together Sept. 1.

A fund has been set up to help the family. Donations can be made at any U.S. Bank or by mail to: Haisley Jo Donation Fund, U.S. Bank, 505 2nd Ave. N., Fargo, N.D., 58102.

History of violence

On the Minnesota side of the Red, just south of the spot where LaFontaine-Greywind's body was discovered, volunteers also found suspicious items at an abandoned farm. Authorities are inspecting the property, which Hoehn and Crews didn't own, as a suspected crime scene.

In addition to conspiracy to commit murder, which carries a possible sentence of life in prison without parole, Crews and Hoehn also were charged with conspiracy to commit kidnapping, a felony, as well as providing false information, a misdemeanor. A judge set bail for both at $2 million cash.

They have been living together for about three years, according to court records of a domestic violence case against Hoehn last year. In that case, Hoehn was charged with pushing Crews into a bathtub during an argument.

Hoehn was convicted of misdemeanor domestic assault and sentenced to 30 days in jail, court records show. In 2012, Hoehn was convicted in Grand Forks, N.D., of felony child abuse. He received a sentence of one year in jail and served 130 days. In that case, according to court records, he was found responsible for the multiple skull fractures his infant son sustained while in his care.

Staff writers John Reinan, Karen Zamora and Elizabeth Sawyer contributed to this report.

Staff Writer Karen Zamora contributed to this story.