A September trial date has been set for a truck driver at the wheel during a deadly 2015 crash on I-75, according to WRCB.

The court decided to reset jury selection for September 21 in Davidson County. The actual trial will happen on September 25 in Chattanooga.

Benjamin Brewer is charged with six counts of vehicular homicide and four charges of assault. Investigators say he was driving a tractor-trailer that didn't slow down in a construction zone on I-75 near Chattanooga and started a chain reaction crash. Among the dead were 31-year-old Tiffany Watts of Morristown and her mother, 51-year-old Sandra Anderson of Rutledge.

His trial was set for this week, but some conflicting test results forced a delay.

Blood tests show Brewer had methamphetamine and amphetamine in his system at the time of the crash, but now the amount in his system is in question.

Brewer's attorneys discovered last week a lab for the National Transportation Safety Board tested Brewer's blood and found half of what the Tennessee Bureau of Investigation's test found.

With the 13 counts against Brewer relating to impairment, Mike Little argued Monday the difference is important to the case.

"Now that there is a new, or subsequent, or a second test that's been brought to our attention, it casts doubt on the TBI's result," he said.

An NTSB crash report, released a year and a half after the crash notes the discrepancy but said a number of factors could have played a role, like a two month difference in when the tests were conducted.

Prosecutors argue, despite the amounts of the drugs in Brewer's system at the time of the crash, it's still illegal.

A jury was selected last week from Davidson County to hear the case, but now a new panel will be selected.

A spokesperson for the Hamilton County District Attorney's Office confirms the jury will once again be selected from Davidson County.

Both sides will meet on June 27 to confirm if the September trial date works.

WRCB contributed to this report.