Lawyers for Casey Anthony are trying to convince a judge that the mom suspected of murdering her daughter Caylee was not properly read her rights and that key statements by Anthony should be thrown out of her upcoming trial.
Among the remarks that could be at risk are Anthony's statement to Florida police that her missing daughter was with a babysitter named Zenaida Gonzales. Police eventually determined that Anthony did not know a babysitter named Zenaida Gonzales.
Losing key testimony like that could make it difficult for prosecutors to get the conviction of first degree murder -- and the death penalty -- that they are seeking.
Anthony's defense is also trying to rule out jailhouse videos and statements she made while in jail where she talks to her family and visitors in the days while Caylee was still listed as missing and before her body was found. The videos show Anthony concerned about legal strategy and not expressing worry about her daughter.
An emotional moment in the hearing came today when Anthony's father George Anthony took the stand to testify about those videos. At one point he was asked by Casey Anthony's lawyer Jose Baez, "Do you love your granddaughter more than anything?"
Instead of answering, George Anthony could only hold his head in his hands and sob.
Casey Anthony reported her daughter missing in July 2008, telling police she had not seen the girl in a month after dropping her off with a babysitter.
Anthony was arrested and charged with murder in October 2008. Her daughter's skeletal remains were discovered in a wooded area near the family's home in Dec. 11, 2008.
Defense attorney Jose Baez had argued that police failed to read Anthony her rights after taking her into custody, and that any statement she made after that should be ruled inadmissible in her murder trial which is scheduled to begin in May.
At one point, Anthony was put in the caged back seat of a police cruiser as she pointed out to police where Gonzales allegedly lived.
The defense attorney argues that talking to police while sitting in the caged section of the police car gives the perception of "a custodial interview," which would require that her Miranda rights be read to her. Baez is also arguing that Anthony was briefly handcuffed, but was not read her rights at that point either. The lawyer zeroed in on the cuffing during a hearing Wednesday.
"Did you advise Casey of her Miranda rights?" Baez said, questioning Orange County Deputy Sheriff Ryan Eberlin.
"No," Eberlin replied.
"Did you witness any other officer reading her Miranda rights?" Baez continued.
"No," Eberlin said.
Casey Anthony Wants Statements Barred From Murder Trial
ABC News legal analyst Dan Abrams said that if the circumstances made Casey Anthony feel as though she were in custody, "they then have to offer her Miranda rights … even if they don't arrest her."
The woman's parents, George and Cindy Anthony, took the stand Wednesday and their daughter cried as she watched while her parents were asked whether their daughter was questioned before or after she was handcuffed.
"Whenever you place handcuffs on somebody ..they are in custody .. you don't just put them on and take them right back off again," George Anthony said on the stand. "I mean technically when you put handcuffs on somebody, you're taking their rights away from them."
George Anthony took the stand again today along with Casey's brother Lee to testify that police asked them to put certain questions to Casey during videotaped jailhouse interviews to circumvent the legal prohibition of questioning her when her lawyer wasn't present.
Lee Anthony testified that he was told by investigators, "We can't talk to her, but you can."
Statements by Casey Anthony that turned out to be false, like the existence of the babysitter, and her behavior during the investigation could be crucial to the case because there is very little direct evidence linking her to Caylee's murder.
Prosecutors appear to be building a case of circumstantial evidence and Anthony's statements and her behavior are going to be key to their attempts to win a conviction.
If the judge agrees that Anthony should have been read her rights sooner, the court could suppress all statements made by Anthony or suppress certain statements.
ABC News' Liz Sintay, Matt Knox and Lee Ferran contributed to this story.