A woman who faces second-degree murder charges after crashing a car into the crowd at an Oklahoma State University homecoming parade, killing four people including a toddler, may be mentally ill, her lawyer has said.
Adacia Chambers, 25, who lives in the college town of Stillwater where the horrific crash happened on Saturday, was originally arrested on suspicion of driving while under the influence of drink or drugs, but has now also been charged with four additional counts of second-degree murder.
But Chambers' lawyer Tony Coleman said his client may suffer from a mental illness. He said she did not smell of alcohol when he met her hours after the crash. Police are awaiting blood tests to determine if she was impaired by drugs or alcohol.
"I absolutely can rule out alcohol," Mr Coleman said, adding that he had spoken to Chambers' aunt, grandmother and boyfriend and all had said she was not drinking.
He added it was his opinion that she suffers from a mental illness and said there were warning signs from her behaviour before the crash, including an inability to sleep.
"She doesn't remember a whole lot about what happened. There was a period where I think she could have even blacked out," he said. Chambers recalls only people removing her from the car and being extremely confused, he added.
Chambers' father, Floyd Chambers, of Oologah, told The Oklahoman newspaper on Saturday that he could not believe his daughter was involved and said she was not an alcoholic.
Witnesses described a scene of chaos as bodies flew into the air from the impact and landed on the road. Three adults and a two-year-old boy were killed and at least 46 others hurt, including at least four critically injured.
The dead adults were Nakita Prabhakar Nakal, 23, an MBA student from India at the University of Central Oklahoma in Edmond, and married couple Bonnie and Marvin Stone, both 65, of Stillwater. Mr Stone was a retired professor of agricultural engineering who had been popular with students, a colleague said.
"He was loved by students and one of the best teachers we had," said Ron Elliott, the former head of the biosystems and agricultural engineering department at OSU. "He just really had a gift for connecting with students and helping them learn."
A man standing next to one of the critically injured at the parade said he recalled a sound and then his stepfather Leo Schmitz was gone.
Mark McNitt, who went to the parade with his wife, mother and Mr Schmitz, said: "All I remember is a gush of wind and then the sound, and then Leo, who was standing next to me, wasn't standing next to me."
Konda Walker, an OSU graduate who was in Stillwater with her sister to celebrate homecoming, said she was only about 50 feet from the crash scene. She said it took her a few seconds to process what had happened. There were bodies and injured people lying "all over the place".
"One woman was a crumpled mess on the road. They turned her over and started CPR. We realised she didn't make it," she said.
Among the injured were nine children 10 years old or younger.
At the corner of the junction where Campbell's car came to a stop, a makeshift memorial continued to grow with balloons, flowers, stuffed teddy bears and candles with black and orange ribbons tied around them, for the school's colours. A handmade sign read: "It's always darkest before dawn. Stay strong."
Anthea Lewis had tears in her eyes as she placed a child's hat with an Oklahoma State University logo at the base of the memorial. One of the injured had been a babysitter for her.
"I've lived here my whole life and this blows my mind," she said. "This is something that doesn't happen in Stillwater."