A criminal complaint released Monday says a Wal-Mart truck driver had not slept for more than 24 hours before he caused a deadly wreck in New Jersey early Saturday.
The crash injured comedian Tracy Morgan, who remains in critical condition. Another comedian, James McNair, was killed.
The truck driver is charged with vehicular homicide. Investigators are looking into what 35-year-old Kevin Roper was doing in the 24 hours before the crash.
In 2012, nearly 4,000 people were killed in crashes involving large trucks. To cut down on that number, the Federal Motor Carrier Safety Administration has been trying to combat one potential cause - driver fatigue.
Last year, new rules took effect limiting the maximum average work week for truck drivers to 70 hours. Drivers cannot start a new work week until they've had 34 hours of rest that include at least two nights of sleep between the hours of 1 a.m. and 5 a.m.
But last week a Senate committee voted to ease some of the rules, arguing that they force truckers to drive during daylight hours. Dave Osiecki, who represents American Trucking Associations, says that delays shipments and clogs the nation's highways during rush hour.
"We're concerned about the safety risk; we're concerned about the productivity lost to the industry because we move America's freight. The trucking industry, whether, you know, the public realizes it or you're ubiquitous, when you go to the grocery store, the groceries are there because truckers are moving at night," saud Osiecki.
Truck operators are currently allowed to drive 11 hours in a 14 hour workday. Many companies, including Wal-Mart, use electronic logs in the trucks themselves to monitor driving hours.
In the last 24 months, Wal-Mart's 7,000 drivers have been inspected 6,000 times. Federal regulators say the company's conduct generally did not raise any red flags.