A Medford nursing home caregiver who failed to attach a resident to a ventilator in 2012, which led to the woman's death, was found guilty Wednesday of criminally negligent homicide, a crime punishable by up to 4 years in prison.

The respiratory therapist, Kethlie Joseph, 63, of Brentwood, who stood facing the jury, showed no discernible reaction as the foreman announced the verdict before a packed courtroom in Riverhead.

Michelle Giamarino -- who was told by the staff of Medford Multicare Center for Living that her mother, Aurelia Rios, 72, died of a heart attack -- wiped away tears as she sat and listened to the foreman deliver the verdict.

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The jury of seven women and five men also found Joseph guilty of failing to report the circumstances surrounding Rios' death to state regulators. They acquitted Joseph of three other charges of neglect, endangering the welfare of a disabled person and falsifying business records.

Rios, who had a tracheotomy, was admitted to the Medford facility's short-term rehabilitation unit in September 2012 to help wean her off the ventilator, which she had depended on to help her breathe when she was asleep, state prosecutor Veronica Bindrim-MacDevitt said. Every night, a respiratory therapist who cared for Rios connected her to the ventilator, until Oct. 25, 2012. On that night, Joseph, who worked at the facility once or twice a month, didn't follow Rios' doctor's order to attach her patient to the ventilator through her tracheal tube.

Joseph and three nurses compounded the error, Bindrim-MacDevitt said, when they failed to help Rios as her pulse rate and blood oxygen level dropped into dangerous territory, and the equipment monitoring her vital signs activated audible and visual alarms. For more than two hours in the early morning hours of Oct. 26, 2012, prosecutors said, Joseph and the nurses ignored those warnings, which were sent to their pagers and to terminals set up throughout the ventilator unit.

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Rios was found dead in her bed by a nurse's aide checking on her about 3:30 a.m.

Prosecutors said the four women and a former director of therapy attempted to cover up Rios' death or their roles in her death by lying to investigators from the nursing home and the state Health Department, which launched separate inquiries.

Besides Joseph, the other four employees on trial are Christine Boylan, 50, of Mastic, former director of respiratory therapy, and the nurses -- Victoria Caldwell, 52, of Medford, Marianne Fassino, 54, of Shirley, and Kimberly Lappe, 33, of Southold.

All four women face various charges, including neglect and falsifying business records. Joseph was the only one charged with criminally negligent homicide.

The circumstances surrounding Rios' death came to light when Stephen Shanahan, a respiratory therapist at the nursing home, reported her death to the state regulators on Nov. 5, 2012.

State Supreme Court Justice John B. Collins conducted one trial but with two juries, one for Joseph and one for the four co-defendants.

The Joseph jury, which began deliberations Monday evening, reached its verdict in the midst of summations on her co-defendants' case.

The second jury, which began deliberations late Wednesday, is scheduled to continue its work Thursday.

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The panel lost a member Wednesday after alternate No. 2 collapsed and temporarily lost consciousness while Bindrim-MacDevitt was summing up her case. Justice Collins dismissed the juror, who was taken away by ambulance but the judge said he was alert and talking.

Justice Collins ordered jurors in the Joseph case not to discuss it with anyone, including reporters. The judge also asked the attorneys and Joseph to refrain from talking to reporters for fear that might interfere with the deliberations of the second jury.

Meanwhile, Joseph, a mother and grandmother, will remain free until she returns to court for sentencing on Sept. 15.