Amidst the courtroom battle to determine who killed Caylee Anthony, another question of identity has emerged: Who is Caylee's father?
The question has become a central issue at the blockbuster trial, in which 25-year-old Casey Anthony faces the death penalty if convicted of killing her two-year-old daughter.
Anthony's lawyers contend that the child drowned in the family's swimming pool and Casey was so overwhelmed after years of abuse she was unable to tell anyone. They've suggested that she's been the victim of incest.
Baez drew gasps in the courtroom Thursday when he asked a DNA expert whether she conducted a paternity test for Casey's brother, Lee Anthony, while working with the FBI in 2008.
Serology expert Heather Seubert said she had run the test and noted that it proved that Lee was not Caylee father.
Jurors didn't hear about it, but investigators also performed a paternity test on Casey's father, George Anthony, and came up with similar results.
Baez's suggestion of incest is only the most recent theory about the identity of Caylee's father.
In 2005, a then-pregnant Casey told a neighbor that Caylee's dad was "just a random one night thing," People reported.
Casey's friends believed that Caylee's father was Jesse Grund, a man she started dating after becoming pregnant. But DNA tests indicated that Grund wasn't the tot's dad.
Casey's pal, Lauren Gibbs, and the defendant's mother, Cindy Anthony, both claim Caylee's father perished in a car accident, the magazine noted.
One of Casey's former boyfriends, 21-year-old Jesus Ortiz, died in a 2008 car wreck. But Ortiz's family was shocked when he was named as a possible father.
PHOTOS FROM THE CASEY ANTHONY TRIAL: