NTSB investigators now say the truck driver who plowed into slowed traffic was using his cell phone at the time.
Investigators say Charles Haskell was three seconds into a phone call when he allegedly slammed into a car at 70 miles per hour.
That set off a chain-reaction crash and led to the deaths of five people.
The report does not say if Haskell was holding the phone or if it was mounted in some way.
Haskell's case is still pending in Wilson County court.