Background: The Williamson County Sheriff's Office's headquarters in Franklin, Tennessee (Google Maps). Inset: Savannah Pierce (GoFundMe).

A woman in Tennessee said she was reuniting with an old boyfriend before she went missing — and then was discovered in a shallow grave, according to her family and authorities.

The Maury County Sheriff's Department has declared that 30-year-old Savannah Pierce was found dead. Authorities are investigating her death, and her family members have shared their beliefs about who is responsible.

Around August, Pierce — a mother of three — left Williamson County, Tennessee, to start living in the county just south, Maury County. Both counties are just south of Nashville.

Pierce's mother, Aleta Peters, told regional NBC affiliate WSMV her daughter recently relayed that she had reconnected with an old boyfriend. The couple had a history of drug problems, Peters added.

On Sept. 14, the boyfriend took Pierce to a hospital after her hand was cut on scrap metal, the mother said. That visit was reportedly mere hours before the victim died.

Authorities have neither identified the boyfriend nor announced charges in the case.

Still, Peters believes she knows how her daughter died.

"They got into an argument and he beat her half to death and then shot her," she told the TV station. "Shot her in the bedroom. She came out of the bedroom, walked down the steps, was asking for help, went out on the porch and laid down on the porch and died. They wouldn't call for help."

Sept. 7 was the last day Pierce was in contact with her family, per WSMV. Peters said she knew something was awry when Pierce didn't answer the phone on her birthday.

Family members said they contacted the boyfriend, and that he told them that Pierce had left their home on a motorcycle with another man. Family members were skeptical, and on Sept. 22, they reported her missing.

A private investigator reportedly volunteered to help them. He found out where she was last seen and where the boyfriend had traveled, and the day after the missing persons report was issued, Pierce was found dead.

"They had wrapped her in plastic and put her in the shallow grave and put rocks on top of her to cover her up," Peters said.