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.
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.
"I just wanted to wake up from this nightmare that I knew wasn't a nightmare. It was real," Krim told jurors. "It's like a total horror movie."
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.
Ortega's lawyers had failed to convince the jury she was not guilty by reason of insanity.
