Adacia Chambers, 25, was initially arrested and detained on suspicion of driving under the influence Saturday. She was later charged wtih four charges of second-degree murder.
Payne County District Attorney Laura Austin Thomas said she does not believe alcohol was a factor in the crash. But she told The Oklahoman that Chambers would likely be charged with driving under the influence of drugs.
The attorney representing Chambers said he believed mental illness, not intoxication, caused the crash.
"She doesn't remember a whole lot about what happened," attorney Tony Coleman told reporters Sunday. "There was a period where I think ... she could have even blacked out," he said.
"I don't believe right now that she was intoxicated," Coleman told The Oklahoman. "I have deep concerns about her competency at this point. I'm not a psychologist or psychiatrist, but I can tell you she's suffering from mental illness."
Police Capt. Kyle Gibbs declined to discuss the evidence against Chambers and asked any witnesses with photos and videos to contact investigators.
Thomas said Chambers would likely address bond conditions before a judge Monday afternoon.
Coleman said family members who were with Chambers late Friday did not see her consume any alcohol. Her boyfriend said she was sober when she left for work at a restaurant about 8:30 a.m. Saturday, he said.
The car was not part of the homecoming parade, according to police. Gibbs said Chambers drove her Elantra through several barriers and hit a parked police motorcycle before careening into the crowd.
Witnesses described a scene of chaos as bodies flew into the air from the impact and landed on the road. Three adults and a 2-year-old boy were killed and at least 46 others were hurt, including at least four critically injured. Hospitals initially said five were critically injured, but one of those was upgraded to fair condition on Sunday.
Chambers' father, Floyd Chambers of Oologah, told The Oklahoman he couldn't believe his daughter was involved and said she was not an alcoholic. He described her as "timid" and said she had attended homecoming festivities Friday night with family, but her boyfriend told him she was home by 10 p.m.
"This is just not who she is. They're going to paint her into a horrible person but this is not (her)," Floyd Chambers told the paper.
Two of the deceased were identified as local residents Bonnie Jean Stone and Marvin Lyle Stone, both 65. A third adult killed was Nikita Prabhakar Nakal, of Mumbai, India. She was a student at the University of Central Oklahoma, according to that school's president, Don Betz.
Oklahoma State identified the 2-year-old boy as Nash Lucas of Stillwater.
Marvin 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," Elliott said in a telephone interview.
The homecoming game against Kansas was played as scheduled, players bowing their heads in prayer as the American flag fluttered at half-staff in Boone Pickens Stadium under orders from Gov. Mary Fallin, an Oklahoma State alumnus who attended the game. The university's homecoming is a major celebration, drawing more than 80,000 alumni, fans and area residents downtown. A pep rally before the game was canceled, said Stillwater Mayor Gina Noble, who was the parade's grand marshal. The undefeated Cowboys beat winless Kansas 58-10.
Noble said the town's 50,000 residents are still in shock.
"We've never seen anything like this. We're taking our time to make sure we get everything right," she said. "We're shocked. We are definitely subdued in mood and we're still trying to understand."
Contributing: John Bacon, Greg Toppo, USA TODAY
