Anthony's parents, George and Cindy, will testify during the trial and Casey Anthony's relationship with them may even be part of her defense.
In jailhouse letters, Anthony told a fellow inmate that her brother, Lee, and father sexually abused her. Anthony's former boyfriend also has made the claim that her father sexually abused her. Using inmates as witnesses could be tricky for the prosecution.
"The prosecution has a lot of evidence and if they put at least one of these jailhouse snitches on the stand...that might allow the defense to cross examine the witness at that point and that brings allegations of abuse against Casey into the courtroom," said Casarez.
Anthony's defense lawyer Jose Baez repeatedly asked jurors during jury selection if they would consider someone for the death penalty who's been abused sexually. The issue of abuse will certainly come up during the sentencing phase of the trial.
"It appears where the defense is angling is it was an accidental death," Hornsby said. "One fork in the road is after they try to establish it was an accidental death."
Hornsby said the defense could pin Anthony's reluctance to come forward about her daughter's disappearance and death because of her fear of her parents and how they would react to her. That would likely not require her to testify, Hornsby said.
The start of the guilt phase of the trial on Tuesday follows 11 days of grueling jury selection and nearly three years of intense media scrutiny surrounding the case.
Judge Belvin Perry expects the eight week trial will draw more interest than the O.J. Simpson trial in 1994.
ABC News' Ashleigh Banfield contributed to this story.