A young girl found dead in a river is believed to be a 5-year-old whose disappearance last week prompted a frantic search, authorities said Thursday.

Searchers found the body Wednesday evening in the Cedar River, a couple of miles from little Evelyn Miller's (search) home in Floyd, county Attorney Marilyn Dettmer said.

A positive identification was pending but Dettmer said it's believed the body is Evelyn, who disappeared last Friday. An autopsy was planned.

Dettmer declined to say who found the body or supply details about its condition. She said no one was in custody in the case and no arrests had been made.

About 1,300 volunteers logged more than 9,000 collective hours in searching for Evelyn for nearly a week, Dettmer said.

Noel Miller (search), Evelyn's mother, has said she left her children, Evelyn, Gabriel, 2, and Damian, 1, with her fiance, Casey Fredericksen, at their apartment in Floyd, a small farming community about 110 miles northeast of Des Moines.

When she arrived home from her overnight job later Friday morning, the apartment door was slightly open and Evelyn was gone.

Mary Neubauer, a spokeswoman for family members, said they are devastated.

"We all believed Evelyn would be found and we'd bring her home safe," she said.

The grandfather, Richard Christie of Des Moines, told KWWL-TV in Waterloo and The Gazette in Cedar Rapids (search) that he learned late Wednesday his granddaughter's body was found.

"She was murdered and her body was put in the river," Christie told the newspaper. "She was not drowned."

Evelyn was last seen by two acquaintances of her mother's fiance about 2 a.m. Friday, asleep on a loveseat in the family's apartment.

Those two men have been questioned by authorities and a search of their home was conducted. Authorities have not called them suspects.

Authorities have said Fredericksen, 26, passed a lie-detector test.

Andy Christie, Evelyn's father, and his wife, Lindsey, said at a news conference earlier Wednesday they still hoped to find the girl alive. They recently found an abandoned puppy and planned to give the pup to Evelyn.

"We haven't named him yet," Andy Christie said. "We are waiting until Evvy gets home, so she can name him."