EXCLUSIVE: Quinton Simon’s baby sitter exclusively told Fox News Digital that she found the boy and his toddler brother alone in the family’s pool over the summer — and now suspects that the missing boy drowned. 

"I felt the whole time that this has happened that Quinton got out and maybe got into the pool," Diana McCarta, 47, told Fox News Digital. "That’s my feelings all along because Zayne can open the door, and they’ve gone out before."

The 20-month-old vanished from the family’s Savannah home Oct. 5, and police said they believe the child is dead and was likely discarded in a dumpster that was emptied at the local landfill. 

Authorities have named the child’s mother, Leilani Simon, 22, as the prime suspect, and her other two children, 6-month-old Sky and 3-year-old Zayne, were placed in foster care.

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McCarta, who had been watching Simon’s three children for about nine months before Quinton’s disappearance, said her 16-year-old daughter found Quinton and Zayne alone in the family’s full-size backyard pool over the summer. The children cannot swim. 

"I go down there, and they was in the pool and we got them out — Leilani was sleeping," she told Fox News Digital. "It was scary." 

After Quinton went missing, authorities drained the pool to look for the child.

McCarta, who has six children of her own, said Simon’s kids were not well-cared for.

"Every time they come over here, we bathed them. They were dirty. We fed them good because they were always hungry," said the sitter who lives across the street. "Definitely, there was neglect there."

The pool incident was not the only time the toddlers had wandered off. A month ago, McCarta said she found Quinton and Zayne playing alone in a ditch two feet from the busy roadway in front of Simon’s home.

McCarta also said it was strange that Quinton often did not want to leave her house.

"Sometimes Quinton would cry when he had to go with his mom," she said. 

Simon and her boyfriend – the father of Sky, Daniel Youngkin – lived with her mother, Billie Jo Howell, who had custody of the children.

Howell, who has a lengthy rap sheet, was granted custody after the court determined that Simon "is a chronic, unrehabilitated substance abuser of cocaine and cannabis," according to documents obtained by the U.S. Sun. 

Simon, who is on probation for shoplifting, allegedly admitted to using cocaine and tested positive for the drug at the birth of one her children. 

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Howell had left town earlier in the week, leaving the children alone with her daughter at night. On Oct. 5, at 5:20 a.m., Simon told McCarta in a text that she would not be dropping off the kids. 

McCarta said at about 8:40 a.m. Youngkin asked her if she had seen Quinton. 

Later that morning, Simon reported the boy missing to police and said Youngkin had been the last person to see him at 6 a.m. 

Police and the FBI interviewed McCarta and searched her trash cans.

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McCarta and her family are heartbroken. "He’s a loving baby," she said. "We’re just praying every day. We’re paying that he is found, that he’s found safe."

The massive search for Quinton has entered its third week. The Chatham County Police Department and FBI have been sifting through the city’s sprawling local landfill looking for the child’s remains.

Chatham County Police have called the search "the most massive undertaking ever for our department."