SAN DIEGO — The caregiver for a 74-year-old man who died in her care and another senior citizen who was allegedly involuntarily locked away pleaded guilty Friday to charges of voluntary manslaughter, false imprisonment of a dependent adult and perjury.

Shirley Montano, 53, will be sentenced to 13 years in state prison for the Oct. 7, 2016, death of Robert Chagas, who died at Sharp Memorial Hospital of pneumonia, which prosecutors argue was exacerbated by severe malnutrition he suffered under Montano’s care. Prosecutors allege she withheld food from Chagas and Josefina Kellogg, causing their health to deteriorate over the course of several years.

Prosecutors allege that while the victims lived with Montano in City Heights and other areas of San Diego, she used their social security checks and other government benefits to buy herself a truck, among other personal purchases, and that she gambled away their money at local casinos.

Montano was initially charged with murder, kidnapping and other felonies prior to her plea on Friday. Sentencing is set for March 6 at the downtown San Diego courthouse.

Prosecutors allege that Chagas and Kellogg were kept isolated from others who lived with Montano and confined to their respective bedrooms. Montano’s niece, who stayed with her for about a year, testified at a preliminary hearing that for the first month she lived at her aunt’s apartment, she was not even aware Kellogg existed because the woman would hardly ever emerge from her bedroom.

Others who resided at Montano’s apartment or visited the home were offered various explanations for the presence of Chagas and Kellogg, according to testimony.

Kellogg testified that she stayed in her bedroom for several hours each day and feared angering Montano, who would hit her if she did not obey the rules of the house.

Chagas was “emaciated” when he was brought into the hospital, where he died five days later, prosecutors said.

Montano, who posed as his niece, told medical personnel that Chagas did not wish to be resuscitated, according to testimony. Chagas’ family members were only notified of his hospitalization after his death, they testified.

Montano’s attorney, Shannon Sebeckis, argued at the preliminary hearing there was no evidence that Chagas’ malnutrition was caused by Montano, and was not the natural result of aging. Sebeckis reiterated the testimony of San Diego County Chief Medical Examiner Glenn Wagner, who declined to classify Chagas’ death as a homicide. Wagner said Chagas was not getting sufficient food, but could not opine as to why, only that it appeared to be due to non- medical factors.

No calls were made by family or medical professionals to Adult Protective Services in Chagas’ case, which also contributed to Wagner’s opinion not to classify his death as a homicide, the doctor said.

While evidence was presented that Chagas once told a doctor that his weight loss was due to not having enough money for food, Sebeckis said this was not proof that Montano was taking his money or withholding food, especially in light of Chagas’ issues with handling his own finances.

Chagas’ family members testified that an accident that occurred at childbirth had left him “slow,” as his brother Richard described it, and that throughout his adult life, Chagas was susceptible to being scammed and had lost exorbitant amounts of money to fraudsters in the past, leading family members to take an active role in assisting him with taxes and paying bills.

Sebeckis argued there was little direct evidence that Montano didn’t feed the seniors, as past roommates said they had seen her providing food for Chagas and Kellogg. The attorney also said Chagas was not confined at all, and regularly left the apartment each day for his janitorial job at Sea World, which he attended with a sack lunch prepared by Montano each day.

The defense attorney also said it was “pure speculation and conjecture” that Montano didn’t use the seniors’ funds to pay for their basic needs.