The older sister of the New York City nanny who butchered two young children testified Monday that the parents were to blame for their kids’ deaths.

Miladys Garcia, Yoslyn Ortega’s sister, said Kevin Krim and his wife Marina should have recognized that Ortega was “unraveling,” and given her a vacation before she slaughtered the children in the Krims’ Manhattan apartment in October 2012, according to the New York Post.

“Why didn’t those parents realize and take her out themselves — they were seeing it,” Garcia said, according to the newspaper.

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Leo Krim, 2, left, and his sister Lulu Krim, 6, from New York. (AP)

When asked by a Manhattan prosecutor to clarify her statement that the Krims’ should have seen the warning signs, Garcia responded, “Yes, because they were the ones seeing her.”

“Give her a vacation if you see she’s losing weight, say ‘Yosie, you’re not yourself.’ Even a week of vacation. Say, ‘Go, Yosie, you’re very thin,’” she added, as the children’s father sat in the gallery listening, reported the paper.

Garcia also said she spoke to her sister just hours before the horrific killings, in which she said Ortega sounded as if she “had become something evil” and that it was like talking to a “demon,” the New York Daily News reported.

When pressed on why she didn’t seek help after the troubling phone call, Garcia said she “didn’t think it was that serious.”

“Why didn’t those parents realize and take her out themselves — they were seeing it”

— Miladys Garcia

Raquel Perez, a friend of Ortega’s said in testimony that she was “very sad and cried a lot” prior to the killings, the Daily News reported.

No one denies that Ortega murdered 2-year-old Leo Krim and his 6-year-old sister Lucia, who went by Lulu, on that day. The key question of the trial is why she did it and whether she was too mentally ill to be held responsible.

Prosecutors have said Ortega planned the killings, waiting until she was alone in the apartment and carefully selecting two knives from the kitchen before dispatching her charges. But they also have admitted that they have no clear motive.

The Associated Press contributed to this report.