In its review, the South Carolina Highway Patrol noted Columbia police investigators did not examine mayor-elect Steve Benjamin's headlights properly and also did not correctly identify marks on the road as part of the accident scene and did not address human factors such as fatigue in their crash report.
The patrol also noted that the 61-year-old woman driving the other car had marijuana in her system, but the amount was so small it would not have impaired her driving.
The patrol had been reviewing the Columbia police department's report on the crash, which occurred just before 6 a.m. on April 21.
Only hours after winning a runoff election to become the city's first black mayor, Benjamin, 40, was on his way to an early morning interview at a television station when his Mercedes SUV collided with a Toyota Tercel a few blocks from the State Capitol complex.
The lawyer and lobbyist wasn't injured.
The other driver, hotel worker Deborah Rubens, suffered brain injuries, a broken collarbone and a shattered pelvis and has been recovering in a hospital for several weeks.
On Wednesday, Benjamin broke more than a month of silence, saying he had paid an $82 fine for driving without headlights. Police also announced they had ticketed Rubens for driving without insurance.
Police have said they did not think Benjamin was under the influence and did not administer any field sobriety tests.
In written statements, Benjamin said he had two alcoholic drinks on election night, the last one around 12:30 a.m., and slept only a few hours.
The sobriety of Rubens, who was on her way to work at a nearby hotel, had not been the subject of much scrutiny. In their notes, the Patrol said tests done at the hospital showed the amount of marijuana in her system was very small and showed she likely had taken the drug several days before the crash.
Benjamin said he and his wife spent the night at a hotel, leaving their SUV with a valet.
Benjamin would not say whether he thought the valet had disabled a setting that would have made his headlights come on automatically when the car was restarted, but Benjamin said Wednesday both he and his wife routinely used that setting.
The wreck spawned more than a month of controversy and led to the firing of Columbia's police chief.