Duley has another child, a five-year-old, who is currently with Duley's mother, said Williams. It was uncommon for Duley to take all three children with her at the same time, said Williams, a condition that likely spared the life of her third child.
Williams said that Duley could "possibly" have been suffering from post-partum depression and experienced many highs and lows of emotion during her interview with police. Duley told authorities that she was unemployed and had "no way of caring for her children," said Williams.
The childrens' father has not yet been located, said Williams, and Duley had been acting as both "mother and father."
Authorities had never truly believed Duley's claims that her car, a Chrysler sedan, had accidently plummeted into the river Monday morning.
The state patrol received a call at 6:15 a.m. reporting an automobile accident near a boat landing on the North Edisto River. But investigators found no evidence of car wreck.
"We felt that the story she was telling us wasn't factual," said Williams. "It was our early determination that this vehicle entered the river by intentionally being placed there."
Duley, who did not have a cell phone, had left the scene and walked nearly a mile before she flagged down a passing motorist to call the police, investigators said. She was first charged with leaving the scene of the crime.
But Williams said today that upon further investigation, it became increasingly clear that Duley's story just didn't match up.
"I think she didn't have no where to go," said Williams. "She's been living with her mother, there was a battle with mom and she wanted control but had nothing to control."
"Nothing to control but her kids," he added.
Duley's story has chilling similarities to the 1994 case of Susan Smith, the South Carolina woman who was convicted in the drowning deaths of her two sons, who were found inside her car, which was submerged in a lake. She claimed the children had been kidnapped by a black man who carjacked the vehicle.
ABC News' Steve Osunsami and Lee Kamlet contributed to this report.