In December, the state's attorney's office filed court papers indicating that prosecutors would not seek the death penalty in connection with the first-degree murder case.
In a notice of intent filed today, prosecutors said additional information has become available. The filing says that "sufficient aggravating circumstances exist to justify the imposition of the death penalty," according to the Orlando Sentinel.
A spokeswoman for Jose Baez, Anthony's attorney, said in a statement, "This is not a death penalty case. We will do whatever is necessary to defend Casey Anthony from the state trying to take her life. We already have death-qualified defense lawyers on our team and are prepared for a vigorous defense."
Anthony, 22, has pleaded not guilty in the death of her daughter, Caylee. She is scheduled to go on trial in October.
The child's remains were found Dec. 11, less than a quarter-mile from the home she shared with her mother and grandparents.
The case started with a frantic emergency call from Casey Anthony's mother, Cindy Anthony, in mid-July.
On the tape, she is heard frantically telling emergency operators, "I can't find my granddaughter. … There's something wrong. … I found my daughter's car today and it smelled like there's been a dead body in the damn car." Casey Anthony then got on the phone and reported she may have a missing child.
Cindy Anthony later retracted that statement, saying that the smell in the car could have been from garbage.
As investigators quickly learned, this would only be the first of many twists and story changes in the curious case.
CLICK HERE for a timeline of the case.
In the original version of events, Casey Anthony 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 both 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 baby sitter Zenaida Fernandez-Gonzalez lived, they found that no one had lived in the apartment for five months.
At that time, investigator Yuri Mellich of the Orange County police department 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.
In a police report, Mellich said that "after several months of investigation, detectives could find no one who has ever met, spoken with or seen any Zenaida Gonzalez who had cared for Caylee Anthony."