Investigators in Iowa probing the death of a 29-year-old mother whose body was found in a cornfield earlier this month said Thursday that the case remains a mystery.

Brandy Shepherd was found dead on Aug. 9, about 20 miles from where she was staying with friends in Mount Pleasant, Iowa. A farmer reported her body to the police after he discovered her in his field, according to KWQC-TV.

The mother of four had been reported missing a week earlier. There were no obvious signs of suicide or homicide, Henry County Sheriff Rich McNamee said.

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“It’s extremely unusual to have a case like this with so little information this far along,” he told KWQC. "I don't want this to turn in a cold case."

Investigators said they had few clues from the scene to go on and an autopsy found Shepherd’s death to be undetermined.

"There were no obvious cases someone had done that," McNamee said. "More forensic studies or toxicology may reveal that. At this point, we don't know." Toxicology results are expected back in a few weeks.

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“Not having results is difficult,” McNamee said. “Difficult from an officer standpoint, difficult obviously from a family's standpoint."