When police arrived to answer a 911 call, they found a man with stab wounds and Stockdill holding a knife.
Police also found the body of her daughter she had apparently been dead for several days.
"The autopsy results are that she died from asphyxia by drowning and the manner of death has been ruled homicide," said James Baroni, chief deputy medical examiner.
Her mother, 25-year-old Blair Stockdill, was arrested on suspicion of murder.
Stockdill had recently regained custody of her daughter. She now faces child abuse and murder charges.
Stockdill's bail was raised to $530,000.
Her arraignment has been continued until Oct. 22.
A memorial was created for the girl outside the home by friends, family and neighbors.
"You see this kind of stuff on the news and you're disgusted, and to have that happen right in front of you to somebody you know it's just really hard to cope with," said neighbor Brittany Quidwai. "She got along with every age. She was a very outgoing, beautiful spirit. It's just a tragedy."