Erin Merdy, 30, was charged Wednesday with three counts of murder in connection with the deaths of her three kids.
For each victim, she is charged with murder, murder with depraved indifference to human life and murder with victim under 11 years old.
On Tuesday, the Medical Examiner said the three kids died by drowning and their deaths were ruled a homicide.
Police have video of Merdy walking the children calmly to the ocean in the middle of the night, according to police sources.
Merdy remained hospitalized at NYU Langone Hospital Brooklyn on Tuesday. If she is unable to be moved to court, a bedside arraignment is possible.
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Authorities are looking into whether postpartum depression that led to postpartum psychosis could have played a role.
Merdy has no documented history of psychiatric problems but the family has made statements insisting she was taking anti-depressants and was off her medication.
Police say she told her family members she drowned her children but won't speak to investigators.
The lifeless bodies of her three kids -- identified as 7-year-old Zachary Merdy, 4-year-old Lilana Merdy, and 3-month-old Oliver Bondarev -- were found on the shoreline of a Coney Island beach after an extensive search.
Police first learned of the children's disappearance early Monday morning, when a concerned family member called 911 saying Merdy called her to say she harmed the children.
When officers arrived at the home on Neptune Avenue, a man who identified himself as the father answered the door and told police he believed the mother was with the children on the boardwalk.
Officers then began to canvas the boardwalk and surrounding area for any sign of the mother or children.
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Ninety minutes later, police got a call from family members who were with Erin Merdy on the boardwalk, about two miles from where the children were found.
The search for the children intensified after Erin Merdy was found alone, and police sent in a helicopter and marine units.
The children were found at the water's edge shortly after 4:30 a.m. on a quiet section of beach about 13 blocks from the stadium where the Brooklyn Cyclones minor league baseball team plays.
Efforts to revive them at a nearby hospital failed, NYPD Chief of Department Kenneth Corey said.
Erin Merdy has prior incidents of harassment and aggravated harassment that did not result in charges, but she has no prior arrests or a history of being emotionally disturbed.
Police say the actions appear to be premeditated and not something that occurred at the spur of a moment, and detectives are looking into her past and interviewing neighbors and relatives to determine what had transpired.
The Administration for Children's Services declined to discuss whether they should have been looking into Merdy before the children's deaths, and if the family slipped through the cracks.
"Our top priority is protecting the safety and well-being of all children in New York City. We are investigating this tragedy with the NYPD," an ACS spokesperson said.
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Eyewitness News also learned that she had been served with an eviction notice, claiming rent had not been paid since sometime last year.