Los Angeles (CNN) -- Former U.S. Commerce Secretary John Bryson will not face charges stemming from two automobile collisions last month, the Los Angeles district attorney's office announced Tuesday, citing insufficient evidence.
In a charge evaluation worksheet released by district attorney spokeswoman Sandi Gibbons, blood tests revealed negative results for alcohol, although a low amount of Ambien, a sleep aid medication, was detected.
According to the summary evaluation, authorities could not determine whether the medication was a factor in the crashes.
Bryson, 68, resigned June 21, telling President Barack Obama in a letter that his June 9 seizure could be a distraction from performing his job.
Bryson had been on a medical leave of absence since his involvement in two separate auto accidents in California that his office indicated were linked to the seizure. Police said Bryson was found unconscious at the wheel of his car following the collisions.
"Based on doctors' opinions there is insufficient evidence to show knowing failure to provide personal information for hit and run," the evaluation stated. "Further, based on blood test and medical condition there is insufficient evidence to prove driving under the influence," according to the statement.
Bryson, who was driving a Lexus, rear-ended a Buick occupied by three men that was stopped at a railroad crossing in San Gabriel, according to a police statement.
"Bryson spoke with the males, then left the scene, hitting the same car again as he left," the statement said.
The men in the Buick followed Bryson while calling 911 to report the accident, it said.
Bryson drove to the neighboring city of Rosemead, where he hit a second car, according to authorities. Police then found him unconscious in his vehicle.
Two of the three men in the Buick were treated for minor injuries, according to police.