"I just want people to know that Adacia is a kind, loving, caring person, and she wouldn't have done this purposely. I just don't believe that in my heart," her father, Floyd Chambers, told reporters.
"Something has happened. I don't know what because the night before she was fine. She was with my sister and my mother and she was happy, so glad to see us," he said. "Something went wrong."
Seventeen injured people remain in the hospital, four of whom are in critical condition.
Payne County District Attorney Laura Thomas said in a statement that prosecutors will consider additional charges in the coming weeks related to the surviving victims.
"Based upon the Probable Cause Affidavit and information presented by the police, the state believes the acts alleged demonstrate a depraved mind and indifference to human life," Thomas said. "The evidence suggests this was an intentional act, not an accident."
Chambers' attorney, Tony Coleman, said his client was not drunk, though he said he's making that determination based on meeting with her hours after the incident.
"I didn't detect any signs nor was there an odor of alcohol coming from her body," he said.
His client had a standard field sobriety test, he said. "Her poor performance" on that test led officers to believe she was "impaired," he said.
Coleman said he believes she may have a mental health issue. When he met with Chambers, he said, she gave "inappropriate answers" to his questions. He also said she had a "flat affect" when reacting to his description of the car crashing into the parade.
"Her answers to my questions were inconsistent, but more importantly the look in her face. There is a very blank, almost lifeless look in her face," Coleman told reporters.
Upon booking, Chambers said she had a history of suicide attempts. She told staff she was suicidal at the time of the incident, but not at the time of booking, according to the probable cause affidavit.
The document also said Chambers had been treated for "mental health related issues" in the past, a fact her lawyer confirmed. Coleman said mental illness runs in his client's family.
He told reporters Sunday that "there have been warning signs coming from Ms. Chambers for quite some time, for the past few years."
Coleman wouldn't elaborate on what he meant by warning signs.
In a brief filed on November 19, Coleman said that Chambers had blood drawn by police after her arrest, and the sample showed a blood alcohol level of 0.01. In Oklahoma, the legal limit for blood alcohol level for drivers over 21 is less than 0.08.
According to both her lawyer and father, Chambers had spent some time at a mental health facility in Wagoner, Oklahoma.
"They had her for a couple of weeks, and they released her, and said there's really nothing else they could do for her. So I took her to another place when she got out of there, and basically the same thing," said Floyd Chambers.
He told reporters his daughter was good at hiding her problems because she didn't want the family to worry.
"She may have problems, underlying problems that I wasn't fully aware of, but we're going to address that," he said.
On Monday, Chambers' boyfriend, Jesse Gaylord, also spoke to reporters. He said he couldn't comprehend what would have caused his girlfriend to drive into a crowd.
He guessed that perhaps she had a medical issue. He also said, "She doesn't handle stress well."
"I would imagine she is just, like, in utter shock and doesn't even know how to process what's going on," he said.
Chambers' next court appearance is scheduled for November 13.
Here's a recap of what happened and an update on some of the victims:
Festive OSU fans
"America's brightest orange." The proud slogan of Oklahoma State University well describes the scene of the crowd lined up on a street, decked out in orange jerseys to cheer their team on against the University of Kansas Jayhawks.
For many, it was a family outing with children in tow. And fans were hopeful for OSU's undefeated Cowboys, nationally ranked No. 10 by USA Today's Coaches' Poll.
The mood couldn't have plunged more dramatically in an instant.
Out of the blue, a car plowed into the masses after bouncing off a parked police motorcycle. From a distance, fans saw the car punching into the crowd.
"I can't describe it any more clearly than this: people flying in the air," OSU graduate student Paul Sims said.
Student Kailey Carter saw the car coming and tried to sprint. It knocked her airborne.
"The car hit me as it was stopping, and then I flew over some strollers," she told CNN affiliate KJRH, holding up a bandaged
Geoff Haxton stood about 100 yards from the crash site watching the aftermath.
"All there was was smoke and panic. Half the emergency personnel in the county were here," Haxton said. "People were running. (My) first instinct was to get my kids away from the street."
Madison Atwell, 7, survived the lunging car with six broken ribs, a concussion and stitches, her family said.
Her aunt, Julie Franklin, said a woman at the scene pushed Madison out of the way. The car took the woman's life instead, Franklin said.
Among the four dead
were Marvin Stone, 65, a retired OSU professor and researcher, the school said. His 65-year-old wife, Bonnie, also died. She had worked for the university for more than 30 years.
The 2-year-old boy who died was Nash Lucas, the son of another OSU employee, Nicolette Strauch, who survived, the school said.
The fourth person killed, Nikita Prabhakar, 23, was visiting Stillwater. She was an MBA student at the University of Central Oklahoma, her school said. Prabhakar was originally from Mumbai, India.
Worried loved ones
At a local hospital, Mark McNitt kept vigil with family on Sunday as loved ones waited to hear the results of surgeries and medical tests performed on the severely injured.
His stepfather, Leo Schmitz, 54, was one of the four clinging to life in critical condition.
"It's been a crazy 24 hours," McNitt said, tearing up. A day before, Schmitz was standing by his side at the parade.
"All I remember is a gush of wind, and then the sound," McNitt said. Then chaos broke out as if a bomb had gone off.
He was thankful for the doctors' work and the care that people from across the state have shown. "We feel the love, and we'll get through this," he said.