In a case that drew national headlines, Yoselyn Ortega, 56, was found guilty by a jury in April of murdering both Lucia Krim, 6, nicknamed Lulu, and her 2-year-old brother, Leo, and leaving their bloody bodies in a bathtub in their luxury Manhattan apartment in October 2012.
Judge Gregory Carro on Monday called the case "pure evil" before issuing the sentence, the stiffest available.
Before hearing the sentence, Ortega addressed the court and apologized. She spoke in Spanish through a translator.
"I'm very sorry for everything that happened ... I ask for a great deal of forgiveness," she said in a shaky voice.
She said she was asking forgiveness from God and the children's parents, adding she had not been feeling well on the day of the murders.
The two-month trial at state Supreme Court in Manhattan featured testimony by the children's mother, Marina Krim.
She recalled the shock of returning to the family's Upper West Side apartment to find her children slain and their nanny standing over them stabbing her own neck with a kitchen knife. Krim had come home with the children's 3-year-old sister, Nessie, after Ortega failed to show up with the children at Lulu's dance lesson.
The motive, prosecutors said, was Ortega's overwhelming financial problems after bringing her 17-year-old son from the Dominican Republic and her resentment toward Marina Krim, married to then-CNBC executive Kevin Krim, for being the mother "she could never be."
In 2012, in the aftermath of the killings, the Krims founded the Lulu & Leo Fund, which supports creativity in schools. Their family now includes two more children: Felix, born in October 2013, and Linus, born in January 2016.
Marina and Kevin Krim left the courtroom before the sentence was read.
Ortega's lawyers had failed to convince the jury she was not guilty by reason of insanity.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)
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