The truck driver who crashed into comedian and 30 Rock actor Tracy Morgan’s limousine van in June 2014 has been held responsible for the accident.
The National Transportation Safety Board said Walmart employee Kevin Roper could have prevented the crash had he been driving at the posted speed limit.
The NTSB said he had been awake for 28 hours at the time of the crash.
They also said the injuries to Morgan and other passengers were exacerbated by their failure to wear seat belts.
The accident on the New Jersey turnpike left Morgan with brain injuries and killed another comedian, James “Jimmy Mack” McNair.
Nine other people were injured in a pile-up that involved 21 people in six vehicles.
Investigators found that Mr Roper’s truck was driving 65 mph in a 45 mph zone when it rear-ended the limousine at around 01:00 on 7 June 2014.
A hearing on Tuesday heard that the Walmart driver had driven 800 miles overnight to the company’s distribution centre before embarking on his delivery.
Investigators recommended that the US retail giant improve fatigue management plans for drivers and install better vehicle warning systems.
Kevin Roper has been charged with vehicular homicide and assault by auto and is awaiting trial in New Jersey.
Morgan reached an “amicable” settlement with Walmart in May, the terms of which have not been made public.
In a recent interview, his first since the crash, the comedian said he had no recollection of the accident and still suffered headaches and nosebleeds as a result.