Adacia Chambers, who drove into a crowd of spectators at the Oklahoma State University homecoming parade, killing four people, has been charged with second-degree murder.
However, the woman’s lawyer said the 25-year-old was not drunk at the wheel of her car, as police suspected, when she hit the people in Stillwater.
“I absolutely can rule out alcohol,” said attorney Tony Coleman, adding his client might have mental problems.
Adacia Chambers is due in court on October 26.
Three adults and a two-year-old boy died, with nine children among about 50 people injured. Five people remain in critical condition.
Adacia Chambers was detained on suspicion of DUI. Police are still awaiting the results of blood tests.
Tony Coleman said she was not intoxicated but added: “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.
“She doesn’t remember a whole lot about what happened. There was a period where I think… she could have even blacked out,” the attorney said.
The four counts of second-degree murder each carry a possible penalty of 10 years to life imprisonment.
Adacia Chambers lives in Stillwater, a town 65 miles north-east of Oklahoma City, but is not believed to be an OSU student.
Her father, Floyds Chambers, told The Oklahoman newspaper his daughter was timid and not an alcoholic.
A vigil to remember the victims was held at the OSU campus on October 25.