A woman whose 79-year-old mother was killed by bedsores pleaded guilty to manslaughter yesterday in Circuit Court.

Nena Lopez, 50, a certified nurse aide, entered the plea in an agreement with the attorney general's office that will require her to serve one to three months in jail and 10 to 20 years of probation .

Deputy Attorney General Michael Parrish, head of the state Medicaid Fraud Control Unit, said the plea agreement was reached in part because the prosecution was the first of its kind undertaken by his office.

"Our statutory scheme does not place a legal burden on the child to care for their parent," Parrish said. "We had to find a section of the law that we believe fit the facts best."

Lopez's lawyer, Deputy Public Defender Edward Harada, said the plea deal "reflects the relative weakness of the state's case and the strength of ours."

If the case had gone to trial, Parrish said, the facts would have shown that Lopez failed to take actions that would have "staved off the massive infection that ultimately caused her mother's death."

Lopez took her mother, Ines Rivera, to a hospital on March 3, 2006, because she appeared to be in respiratory distress.

Medical personnel discovered that Rivera had five substantial bedsores, "three of which were so severe that the bones underlying the sores had begun to liquefy," Parrish said.

Rivera died six days later of sepsis.

Bedsores, clinically called decubitus ulcers, develop on skin covering bony prominences like the lower back, hips and shoulder blades, according to Parrish.

The sores appear when the skin is under constant pressure for a long time and the patient can't move without assistance.

Untreated ulcers are serious sources of infection.

"If the infection is too far along, as it was with Lopez's mother, the patient can die from septic shock — a massive organ failure," Parrish said.

Lopez cared for her mother at home in Waipahu but worked full-time at a geriatric long-term care facility and knew how to care for bedridden patients, according to the prosecution.

Lopez "knew the consequences" of her actions, Parrish said.

Lopez was indicted on a charge of manslaughter by omission in 2007 but Circuit Judge Richard Perkins dismissed the case. Defense lawyer Harada argued that the grand jury was not presented with evidence of what specific duty, if any, Lopez had to care for her mother.

The state then reindicted Lopez on five counts of manslaughter that included four different theories of manslaughter by omission, defense lawyer Harada said.

"They were some pretty far-out legal theories," Harada said, including one that Lopez was "a de facto care home operator, which was absolutely not the case."

Circuit Judge Glenn Kim dismissed all but the top manslaughter charge and Lopez elected to plead guilty to avoid trial.

Many manslaughter plea agreements require at least a year in jail and if Lopez had gone to trial and been convicted, she would have faced six to 20 years behind bars.

Harada said he felt Lopez had a strong chance of prevailing at trial.

"No matter how strong the case, there's always a risk and the risk here was pretty awful — 20 years," Harada said.

"It's not my life I'm playing with. I advised her to take the agreement and get on with her life," Harada said.

Judge Kim will sentence Lopez May 19.