Investigators believe a young Florida boy hid inside his mother's SUV without her knowledge Saturday before he overheated and died.

Investigators say Gregory Cesar's mother, 29-year-old Mirlande Jean-Baptiste, was preparing for her wedding Saturday when she and her sister, Juliana Jean-Baptiste stopped to meet a friend.

A Palm Beach County Sheriff's Office spokesperson says the women dropped off four children, Gregory included, with the friend.

Detectives believe the boy got out of the vehicle, but may climbed back in to his mother's SUV without his mother or aunt noticing.

The women then went to a nail salon in suburban West Palm Beach.

Three hours later, they returned to their Ford Expedition and found Gregory unconscious in the back seat.

The boy's mother called 911 and told the dispatcher her son was breathing but was unresponsive.

After the mother and aunt performed CPR, paramedics took over and rushed Cesar to a nearby hospital where he was pronounced dead.

A day after Mirlande Jean-Baptiste was supposed to be married, she was comforted in her home by family and friends from church.

Investigators say the mother has been too upset to speak to detectives at length.

Charges have not been filed.

Investigators say the friend who was supposed to be watching Gregory noticed he was missing but did not call the mother to ask his whereabouts.

Investigators are waiting for toxicology reports from the autopsy to determine the exact cause of death.