The medical examiner's office shed light Saturday on the Thursday stabbing deaths of two children on the Upper West Side.
The medical examiner said Lulu Krim, 6, died of multiple stab wounds.
Her 2-year old brother, Leo Krim, died of wounds to the neck.
Both were later found in a bathtub by their mother.
Police are still investigating the accused nanny, who was watching over the two kids.
Mourners have been leaving flowers outside their La Rochelle building on 75th Street near Columbus Avenue.
The nanny, Yoselyn Ortega, was also found with self-inflicted wounds on the bathroom floor.
"We believe now that the nanny began to stab herself as the woman entered the bathroom," said Police Commissioner Ray Kelly. "We initially thought that it had already been done but now information is coming out that she did it as the mother entered the bathroom."
Police are looking into a tip that the nanny may have sought psychological help before the stabbings.
Police say charges are pending against the nanny, who remains in the hospital in critical condition.