SALEM (AP) - The Oregon Supreme Court has overturned the manslaughter conviction of Karla Crosby, a Portland woman sentenced to 10 years in prison after being convicted of killing her 76-year-old mother by neglect.

The court reversal Thursday turned on the word “risk” and said the trial judge should have told the jury that manslaughter required a finding that she understood that her neglect risked killing her mother.

But the court said the judge gave an instruction that allowed the jury to convict Crosby for simply risking development of bedsores, which contributed to the death.

“The two risks are very different,” Justice Paul J. De Muniz wrote for the unanimous court.

Norm Frink, a chief deputy Multnomah County district attorney, said his office intended to retry Crosby, who was the sole caregiver of her ailing mother, Sheila, at the family's dilapidated house.

Karla Crosby drove her mother to an emergency room in late 2001, telling doctors that her mother was having difficulty swallowing.

Sheila Crosby also suffered from dehydration, malnutrition and dementia and died a week later from bacterial invasions that poisoned her bloodstream and shut down major organs.

Karla Crosby was later charged with murder-by-abuse and manslaughter.

Prosecutors said during the 2002 trial that there was no evidence that she tried to kill her mother but called the situation the most graphic and horrifying case of elder abuse they had seen.

Photos of Sheila Crosby soon before her death showed an emaciated woman covered with sores, some exposing bone.

Family friends said she was trying to abide by her mother's wish to avoid nursing homes. Prosecutors said doctors had repeatedly urged her to seek outside care for her mother.

Jurors saw a video and photos of Sheila Crosby's feces- and urine-stained bed.

The jury acquitted Karla Crosby of the more serious murder-by-abuse charges.

No new trial date has been set.