Six-year-old Lulu Krim never showed up for her dance lesson.

When her panicked mother, Marina, rushed home at 5:30 p.m. to find out why, she walked into a scene of unimaginable horror: Lulu and her 2-year-old brother Leo were in a bathtub bleeding out from multiple stab wounds. Their nanny, Yoselyn Ortega, was standing over the children’s dead bodies, knife in hand, stabbing at her own neck.

“[Ortega] did it intentionally,” Assistant Manhattan District Attorney Stuart Silberg charged during closing arguments on Monday, after 10 weeks of grisly testimony about the October 2012 killings. “With full understanding of exactly what it was she was doing. Every stab every slash each one had a purpose. That purpose was to end the lives of those children.”

Ortega is accused of stabbing Lulu and Leo in the family’s Upper West Side luxury apartment over resentment and anger at the family. She’s been charged with two counts of first-degree murder and two counts of second-degree murder. If found guilty, she could face a maximum sentence of life in prison.

Prosecutors allege Ortega, whose fate is now in the hands of a Manhattan jury, was upset about being given more housework and being asked to do additional part-time work for a family friend. They claim Ortega was overwhelmed by financial concerns, since she had brought her 17-year-old son to New York from the Dominican Republic and enrolled him in a private school.

But defense lawyers for Ortega—who pleaded not guilty by reason of insanity in state Supreme Court in Manhattan—say the former nanny is mentally ill and should not be held responsible for the brutal stabbings. The 55-year-old could face life in a psychiatric facility if the jury finds her not guilty by reason of insanity, Reuters reports.

In closing arguments, prosecutors alleged that the slayings were premeditated and deliberate—and Ortega was well aware of the consquences of her actions.

“That little girl twisted and turned and did everything possible to stay away from the point of that knife,” Silberg said. “She was unsuccessful, and she was unsuccessful because this defendant was determined to end her life, to cut her throat.”

Ortega’s defense attorney, Valerie Van Leer-Greenberg, repeated in court on Monday that the defendant has suffered for years from depression, psychotic thinking, and hallucinations of “the devil.” Ortega’s lawyers have claimed “the devil” told her to kill the children.

“She who is fighting demons could not see to it that she did not become a demon,” Van Leer-Greenberg told jurors.

A psychiatrist for the defense, Dr. Karen Rosenbaum, has testified that Ortega told her she heard voices that “told her to kill people, to kill herself and, eventually, to kill the children.”

Ortega allegedly told Rosenbaum that she never told her employers about her mental health problems because she was afraid she’d be fired and “didn’t want people to know she is crazy.”

“She struggled—she didn’t want to carry out the plans,” Rosenbaum reportedly said.