Yoselyn Ortega, 55, is on trial for allegedly killing Lucia Krim, 6, and Leo Krim, 2, in their family’s Upper West Side apartment, before slashing her own throat. The prosecution is expected to present Ortega as the Krim family's trusted nanny who knew what she was doing when she repeatedly stabbed Lucia and Leo on Oct. 25, 2012 while the children's mom was out of the home with a third child.