Investigators said Thursday that a driver whose semi rammed into vehicles stopped at a Chattanooga construction site, killing six, was new on the job.
NTSB spokesman Pete Kotowski said Benjamin Brewer was making his first run for Cool Runnings Express at the time of the wreck a week ago at the Ooltewah exit of I-75.
He had begun work for the trucking firm the previous Monday.
The investigator said Brewer passed a drug test prior to being hired.
He said the day before the Chattanooga accident that Brewer sideswiped another truck in Florida. His truck had to be towed for repairs.
The investigator said truck drivers are required to get drug tests after wrecks, but Brewer did not do so.
He said there were several warning signs of the upcoming construction project.
Two different blood samples were taken from the driver, and his cell phone was also confiscated.
There were deficiencies in the truck, but none that should have contributed to the crash, it was stated.
The investigator said Brewer and his passenger were interviewed in Kentucky on Wednesday and were cooperative.
A preliminary report on the accident is expected in 10 days, though the full report will take at least a year.