Bryson resigned from President Obama's cabinet on June 21 after revelations that he had crashed his Lexus into another car, drove away and then crashed into a second car minutes later in a neighboring city.
The Los Angeles County District Attorney's Office released the one-page report on Tuesday afternoon to explain why prosecutors decided not press charges. It said an admitting doctor and a neurologist both examined Bryson, 68, at the hospital after the crash and he was diagnosed with having had a seizure.
"Both treating doctors agree that suspect was suffering from confusion following a seizure and crashed as a result," the report said.
On Monday, investigators with the San Gabriel Police Department submitted charges to prosecutors along with toxicology and medical reports. However, it was up the district attorney's office whether to follow through with the charges.
The decision follows weeks of mystery surrounding what happened that night. Previously, a White House spokesman said some sort of seizure played a role in the collisions but stopped of short of saying it was the cause. Police meanwhile refused to rule out anything, including that drugs may have played a role.
Read the report: