Caylee Anthony's Grandparents Mark Birthday

Timeline: Caylee Anthony Case

Casey Anthony has pleaded not guilty to first-degree murder charges of her daughter Caylee and remains behind bars in Orlando. 

ORLANDO, Fla. – The grandparents of Caylee Anthony, the toddler whose death led to the year's most high-profile murder trial, gathered with more than 100 members of the public to commemorate what would have been the child's sixth birthday.

The Orlando Sentinel reports that the crowd met Tuesday in George and Cindy Anthony's Orlando-area neighborhood, near a wooded area where the little girl's remains were found in December 2008.

"This is the first time I've been here in so long," George Anthony told reporters a few feet from where his granddaughter's body was found. "It's hard to come here."

"Happy birthday Caylee," some people joined in saying as the crowd released dozens of purple balloons into the air.

The appearance of George and Cindy Anthony was a surprise to some. Wearing t-shirts featuring a photo of Caylee surrounded by the words, "You will always remain in our hearts," they led a walk and accepted greetings from well-wishers.

"I am glad because it seems like they're getting a little bit of closure with the crying and different things and I think that's really, really good for them," Lori Richards of Daytona Beach told the newspaper.

But some carried signs criticizing a jury's acquittal last month of their daughter Casey Anthony on murder charges in the child's death. Casey Anthony was released from jail and has vanished from public view.

Still, the event mostly focused on the child whose life was tragically cut short. "May Caylee's memory always live in our hearts," one sign read.

Bring Kids Home, a nonprofit group that helps missing and abused children, wants to build a memorial at the site. The project, set to be designed by artist Jefre, would center on a reflecting pond with a glass ring hanging over it like a halo. It would incorporate elements of A. A. Milne Winnie-the-Pooh books, and would feature cubby holes along a path for visitors to leave stuffed animals and other items that could in turn be given to children's charities. Glass disks would contain the names of missing children.

The nonprofit hopes to raise $200,000 in donations and the memorial would need county approval.

The Anthonys said they hadn't seen the memorial design before, but that they'd support it if it were done tastefully. The event was concluded with a moment of silence and a prayer for missing children.