NEW BRUNSWICK, N.J. >> Accident investigators are looking into what role the work commute of the driver charged in the accident that injured comedian Tracy Morgan played in the fatal crash on the New Jersey Turnpike.

Wal-Mart driver Kevin Roper, who pleaded not guilty to death by auto and assault by auto charges Wednesday, lived in Georgia, but his job was based in Delaware, NTSB spokeswoman Kelly Nantel said.

A criminal complaint alleges that the 35-year-old Roper, of Jonesboro, Georgia, hadn’t slept for more than 24 hours before the accident when he allegedly swerved to avoid slowed traffic on the turnpike and plowed into Morgan’s limo on Saturday morning.

Wal-Mart has not explained what Roper’s driving route was. The company has said it believes he was in compliance with federal safety regulations.

Roper’s bail was kept at $50,000. Roper and his attorney, David Glassman, refused to answer reporters’ questions after the hearing about whether Roper was the author of tweets from a Twitter account bearing his name and featuring his picture and calling reports of his not having slept for 24 hours before the accident “complete BS!”

A conviction on a death by auto charge carries a five-to-10-year prison sentence. Each assault by auto charge is punishable by up to 18 months in prison.

The 45-year-old Morgan suffered a broken femur, a broken nose and several broken ribs. His friend and fellow comedian James McNair was killed, and two other passengers were seriously injured. Another passenger was treated and released from the hospital Saturday, and the limo driver and one more passenger weren’t injured.

Morgan underwent surgery for his broken leg and remained in critical but stable condition.

State police on Tuesday released audio recordings from three 911 calls made after the accident.

“It’s a terrible accident,” a woman tells the dispatcher in one of the calls. “The car flipped. It’s on its side. It’s two vehicles and a Wal-Mart truck.”

Citing the criminal investigation, a Wal-Mart spokeswoman wouldn’t say where Roper’s trip had originated or where he was headed at the time of the crash.

FX Networks issued a statement saying Morgan’s new TV series, a half-hour comedy scheduled to start filming in August for a January premiere on the FXX network, would be waiting for him once he’s well.

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Associated Press reporter Joan Lowy reported from Washington, D.C.