"This was his first dispatch and run for this particular company and after his application was returned,that he had a negative pre-employment drug test that he was authorized to drive a commercial motor vehicle, " says the NTSB's Pete Kotwoski on Benjamin Brewer.

Brewer is the 39 year old truck driver involved in the chain reaction crash that left six people dead and six more injured in last Thursday night's deadly pile-up on I-75.

Kotwoski is NTSB's lead investigator on the crash and says the final report could be a year or more away.

"In aviation, we talk about the black box that tells you everything about the operation," says Kotowski in a hastily called news conference Thursday, a week after the crash.

"Motor vehicles and trucks don't have that, but they have various components that can provide you information about the crash."

Kotowski says his team has retrieved information from 8 of the 9 vehicles involved, surveillance video from neighboring businesses, as well as victim and witness statements, including Brewer.

"We contacted the driver, we interviewed the driver and his passenger yesterday in Kentucky, and they were very cooperative with us," said Kotwoski, who went on to paintsa troubled picture of Brewer's first week on the job.

Brewer was hired Monday in London, Kentucky and the following day, picked up his first load in nearby Horse Cave, Kentucky.

"While there, he encountered some problems and maintenance issues with his commercial motor vehicle and it was down for repairs," stated Kotowski.

The following day, en route to his delivery in Florida, Kotowski says Brewer was involved in a crash with another commercial vehicle in Wildwood, Florida. But according to Kotwoski, Brewer did not undergo a post-accident blood alcohol test as required by law.

"The crash he was involved in in Florida was considered a tow away crash, because he had to have repairs done to his vehicle before he could move it," explains Kotowski.

"He was issued a citation in that crash so he met the criteria of a requirement."

The following day some 580 miles away in Ooltewah, Brewer's next crash would prove fatal.

Chattanooga Police Sergeant David Allen says Brewer was tested after the deadly pile-up near Ooltewah and they await those results.

"They don't happen overnight , the TBI is trying their best to expedite it as quickly as possible. But it is going to take a few weeks so again, we just ask for patience," said Allen.

Kotwoski says his investigatory team has found deficiencies with Brewer's tractor trailer but none are considered contributory or causal to the Ooltewah pile-up.

The National Transportation Safety Board's final report on the Ooltewah crash is expected in 12 to 14 months per Kotowski.

Sergeant Allen with CPD says their criminal investigation will likely take less time than the NTSB's.

We tried contacting Benjamin Brewer for comment, our calls have yet to be returned.