For more coverage visit CNN affiliates WIS, WOLO and WLTX.
(CNN) -- Shaquan Duley wanted to be free, police say.
That is why, they say, she pressed her bare hands over her children's faces, two little boys, and smothered them. That is why she placed their bodies into her Chrysler sedan and sent the car into the blackwater of the Edisto River.
Early Monday when police responded to calls about the submerged car, the 29-year-old mother initially lied, investigators said. She said she had been driving along a country road outside Orangeburg, South Carolina, and had lost control of her car. She told police she walked nearly a mile before flagging a motorist who called for help.
Police were immediately suspicious of the story. There were no signs Duley had been in the water.
During questioning, the mother admitted that she smothered her children, Orangeburg County Sheriff Larry Williams said Tuesday morning.
Video: 911 tapes of children in river released
Video: Car sinks with boys inside
"She would break down to some degree then get back to talking again," said Williams, saying that Duley would have moments when she was totally calm and remarked, 'I don't know what got into me.'"
"The mom has been basically a good mom," the sheriff said. "For whatever reason, this was her weakest moment."
Details about Duley's life are scant. Police say she was living with her mother and has another child, a 5-year-old, whom the grandmother is now looking after.
Williams described Duley as financially desperate, overwhelmed, a "young lady in trouble, in trouble in more ways than she realized."
"She was a mother that was unemployed," said Williams. "She had no way of taking care of her children."
"We believe that her thoughts were for me to be free and to do what I wish to do, whatever that may be, if I didn't have the children, I will get rid of them," he said.
The police are looking for the father of Shaquan Duley's children. It's unclear if he was a presence in her life or in the boys' lives.
She had recently argued with her mother over parenting, the sheriff said. Their arguments were heated, with Duley's mother often pressuring her to be a more "reliable" mother, said Williams.
"Her mother [Duley's] was a very, I guess, firm individual," Williams said. "She often talked with her daughter about, I guess, maybe being more of a mother or being more reliable."
The news about the little boys in the river swept through Orangeburg, a town of 13,000 about 40 miles south of Columbia. The boys' deaths were remniscent of the 1994 case in Union, South Carolina, in which Susan Smith killed her sons Michael Daniel Smith, 3, and 14-month-old Alexander Tyler Smith. She strapped them into their car seats and sent the vehicle into a lake.
"Whatever compelled Shaquan to do what she did, God Lord, please be with her," said Grace Simpson, an assistant manager of Dairy-O, a fast-food restaurant where Duley worked a few years ago as a cashier.
Simpson said she thinks Duley's 2-year-old had not been born then.
A Dairy-O employee for three decades, Simpson pays attention to employees who come and go.
"Shaquan was always coming to work, chipper, make little jokes and would never one to lash out at you. She was a good worker. She stayed here for two years," said Simpson.
"This job will test you, now. There'll be customers who gonna test your patience, but Shaquan had control," she said.
"I cannot judge Shaquan. I will not judge her. Our prayers are with her but I wish she would have taken a different approach if things had gotten so hard," Simpson said.
The South Carolina Department of Social Services has no record of involvement with Shaquan Duley, department spokeswoman Marilyn Matheus said.
After arguing with her mother, Duley drove with her boys to The Trumps Inn on U.S. 301, police said. The owner of the hotel said Duley checked in around 1:30 a.m. Monday; the hotel employee who checked her in said they never saw the boys, CNN affiliate WLTX.
The hotel owner said Duley acted "scary" and "nervous," as she was getting her room and that Duley's car was gone by 6 a.m., according to WLTX.
Investigators went to Trumps Inn and retrieved several bags of evidence from room 31, the affiliate reported.
Tuesday morning, as Duley sat without bond in the county jail, facing murder charges, visitors began laying flowers along the Edisto where the boys' bodies were found.
It wasn't immediately known whether Duley had retained an attorney. She is scheduled to be arraigned Wednesday.
From her home along the water, 81-year-old Ramona Milhouse can see the area where the car sank. She keeps looking out there.
"I couldn't sleep last night, won't sleep tonight either," she said."Thinking about those boys."
