The Wal-Mart truck driver who allegedly caused the crash that critically injured Tracy Morgan and killed comedian James "Jimmy Mack" McNair pleaded not guilty on Wednesday (June 11) to charges of assault by auto and a charge of vehicular homicide.

A criminal complaint alleges that Kevin Roper, a 35-year-old trucker from Jonesboro, Ga., hadn't slept for more than 24 hours before the accident when he allegedly swerved to avoid slowed traffic on the New Jersey turnpike and crashed into Morgan's limo van last Saturday morning (June 7).

Roper and his attorney, David Glassman, refused to answer reporters' questions after the hearing about whether Roper was the author of a Twitter account that's been tweeting out information about the fatal car crash.

If Roper is found guilty of the charges, he faces a five-to-10-year prison sentence. Each assault by auto charge is punishable by up to 18 months in prison, according to the Associated Press.

As of Tuesday (June 12), Morgan is reportedly in "critical but stable condition" with several broken ribs, a broken femur and a broken nose. The 45-year-old comedian recently had surgery to a repair a broken leg.

Morgan's assistant, Jeffrey Millea and comedian Ardie Fuqua Jr., also remain in critical condition, said a hospital spokesman.

The hip-hop community took to Twitter to express their shock and well wishes for Morgan after the crash.