2 causes of death offered in Caylee Anthony case

Casey Anthony cries as she listens to her defense counsel during the opening statements in her murder trial at the Orange County Courthouse on Tuesday in Orlando, Fla.

ORLANDO, Fla. -- Prosecutors and a defense attorney for a Florida mother charged in the death of her 2-year-old daughter each presented new, vastly different theories of how the little girl died as the trial for Casey Anthony began Tuesday.

For the first time, prosecutors said Caylee Anthony died from three pieces of duct tape being placed over her mouth and nose while a defense attorney for the mother claimed the toddler drowned in the family pool and the little girl's grandfather helped cover up the accident.

Casey Anthony, 25, is charged with first-degree murder. If convicted, she could be sentenced to death.

An autopsy was never able to conclude a cause of death for Caylee.

Casey Anthony waited a month before telling her mother that Caylee had disappeared during the summer of 2008, and that was only after her parents, George and Cindy Anthony, had recovered a car Casey had been driving, prosecutors said. The vehicle, which the grandparents picked up from a towing lot, had a foul odor inside.

During the month Caylee was missing, prosecutor Linda Drane Burdick told jurors Casey went shopping, visited friends and hung out with her boyfriend. She also described Internet searches done on a computer at Casey's home that showed queries for chloroform, neck-breaking and alcohol.

"Casey Anthony ... appeared to be ... a loving mother, trying to provide support for her daughter," Burdick said. "But as the evidence in this case will show, that was an illusion."

Casey previously said a baby sitter kidnapped the girl, but her attorney suggested a different set of events.

Casey's attorney, Jose Baez, said she was molested by her father as a child, an allegation George Anthony denied on the witness stand. George Anthony also told jurors that Caylee didn't die at his house, and he denied disposing of her body and placing duct tape over her face.

Baez also claimed that Casey's brother made advances toward her and was given a paternity test to see if he was Caylee's father. All those secrets eventually led to the cover up of Caylee's drowning, Baez said.