Caylee's mother, Casey Anthony, 22, is behind bars.
She's a person of interest in the case, which is beginning to look like a homicide, prosecutors say.
Sheriff's deputies say they still hope to find Caylee alive.
Casey Anthony is charged only with child neglect, lying to investigators and obstructing a criminal investigation. A circuit court judge in Orlando, Stan Strickland, set her bond at $500,000 Tuesday, saying the law didn't allow him to hold her without bail.
He set the unusually high amount after hearing about evidence of human decomposition allegedly found in Anthony's yard and car.
"Not a bit of useful information has been provided by Ms. Anthony as to the whereabouts of her daughter," Strickland said. "And I would add that the truth and Ms. Anthony are strangers."
Authorities say Anthony didn't report Caylee missing until last week, and only then at the insistence of her own mother, Cindy Anthony.
On The Early Show Thursday, Cindy told substitute co-anchor Lara Spencer that a woman had called Cindy to say she'd seen a girl in the Orlando airport on July 2 who may have been Caylee.
"This lady that came forward stated that Caylee spent at least 10, 15 minutes with her (at the airport where, the woman said, the girl was to board a flight to Atlanta) -- her and her son and her husband. Caylee loves playing with puppies, because she has two of her own. And they asked the little girl what her name was, and she said 'Caylee.' And they said they couldn't figure out her middle name, because she ran it, and her last name, Antony. And when she says 'Caylee Marie Antony,' that's exactly how she says it. She can say 'Caylee,' she can say 'Marie' and she can say 'Anthony' very plain, singly. But when she says her name, and she's excited about saying her name, then it's 'Caylee Marie Antony.' "
"When I got back from the courthouse the other night, she (the tipster) was in my voice mail. She stated that she had tried for a couple of days to get through the line. The lady was frustrated. I told her to check with me the next morning if no one had contacted her. She called me several times the next morning and said no one had contacted her."
The woman who gave her the tip was to meet with Orange County sheriff's detectives and a sketch artist to try to come up with a composite sketch of the older woman who was with the little girl in the airport, Cindy told CBS News.
Cindy says the family is "working on" raising her daughter's bond to get her out of jail.
There will be 14 billboards erected across Florida, two in Orlando, with the Caylee's picture on them, Cindy adds.
Sheriff's deputies have said Anthony's car smelled of decomposition, and a cadaver-trained German shepherd noted a smell of human remains in the car and her yard. They said they found a stain, dirt and what seemed to be Caylee's hair in Anthony's trunk. A search of the yard turned up no body.
"The risk of her flight if she is released on some low bond increases exponentially, especially now that she's heard this additional evidence and that she is their person of interest," said assistant state attorney Linda Drane-Burdick at the Tuesday hearing.
Deputies emphasized they were still looking for the girl -- alive -- and urged anyone with information to step forward.
Defense attorney Jose Baez requested bond around $10,000. He said Anthony's family can't pay a high bond and she has the right to freedom while facing lesser charges.
"This is not a capital case, and if it were they certainly would file it, if they had evidence to," Baez said. "There is circumstantial evidence of a possible homicide, I will give them that. But circumstantial evidence has not made them confident enough to charge her with any specific homicide or kidnapping, or any capital offense."
Anthony's parents became concerned after her car was towed from a check-cashing business where it had been parked for days. She and the child lived with her parents, and she told them she worked as an event planner at an area theme park.
Investigators say Anthony was unemployed, and a purported babysitter seems to never have existed. The mother and child hadn't been home in the month before investigators were notified that Caylee was missing. Investigators believe the girl's father is dead.
Cindy Anthony, acknowledged in court that her daughter had lied before, but said she was a caring mom. The registered nurse believes the girl is alive, and Casey Anthony lied to police because she was somehow threatened. Cindy Anthony said she would even sell her house to free her daughter.
"I know Casey as a person," she said. "I know what she is for a mother and I know there's only one or two reasons why Casey would be withholding something about Caylee. I believe that it's something that someone is holding over her and threatening her in some way."
Casey Anthony's face filled with tears at the hearing, watching her parents at the witness stand and again after Strickland set bail.
"Casey, we love you!" yelled Cindy Anthony as the courtroom cleared.
Her daughter nodded and sobbed before being led away in chains.
If you think you may have information about Caylee's whereabouts, call the Orange County, Fla. crime tip line, 1 800 423 8477. There is a reward in the case.