In the original version of events, Caylee's mother reported her missing to police, saying she had dropped the child off at a baby sitter's house June 9. When she went to pick the child up, both the child and the baby sitter had disappeared.
Casey Anthony's parents corroborated the story until a bond hearing July 25 when Cindy Anthony said that the last time she saw the child was not June 9, but June 15, and that she had just been confused.
When police questioned Casey Anthony about her daughter before her arrest, they say she misled them multiple times.
When she took police to the apartment where she said the baby sitter Zenaida Fernandez-Gonzalez lived, they found that no one had lived in the apartment for five months.
At that time, lead investigator Yuri Mellich said, "I am not disregarding that this person may or may not exist, but Casey Anthony's friends and family have never met this person."
After an extensive search for Gonzalez, a woman with the same name came forward in September to tell authorities she had never met Casey Anthony or Caylee. Police cleared her of any involvement.
Casey Anthony also claimed to have worked for Universal Studios but admitted later that was not true.
Scientists found evidence of body decomposition and traces of chloroform in Casey Anthony's car trunk, according to forensics reports released in October.
Lab reports from the FBI found that a hair strand in the trunk showed "characteristics of apparent decomposition." The hair is "microscopically similar" to hair strands found on Caylee's brush, but the report said it could not conclusively say the hair in the trunk came from the missing girl.
Casey Anthony had been considered a "person of interest" in her daughter's disappearance since mid-July after police reported in a bond hearing that they believed they found evidence of decomposition in the car.
But what unsettled investigator Padilla more than Casey Anthony's imprecise information was her overall attitude.
"She has shown no emotion," Padilla told ABCNews in July. "That's unusual. At the time of the interviews ... she didn't seem concerned and that made this case much stranger."
"She spoke to deputies like she was talking about baseball. How do you get through to someone like that?"
But Casey Anthony revealed an entire range of emotion in videos of jailhouse conversations between her and her parents, which were released Dec. 5.
In the more than 300 minutes of video released by the Orange County Sheriff's Department, Casey Anthony is shown laughing, crying and growing frustrated with the investigation and her family's questions.
When her mother confronts her with Mellich's suspicions that she had had something to do with Caylee's disappearance, her daughter dodges the issue.
"Yuri [Mellich, the lead detective,] has it set in his mind. He thinks you've done something to Caylee," Cindy Anthony tells her.
At that point, her daughter gets up and, when she returns, steers the conversation in a different direction.
Casey Anthony also says that she knows the conversations are being recorded and says, "There are things [she] directly needs to say" to each of her parents.
And to her missing daughter, Caylee, Casey Anthony asks her mother to pass along a message that "Mommy loves her very much, and that she's the most important thing in this entire world to me. And to be brave."