E! News obtained the criminal complaint filed against Roper on Monday, which states that the 35-year-old truck driver caused the tragic wreck by operating a vehicle "without having slept for a period in excess of 24 hours."
Roper, who is currently free on $50,000 bail, is expected to appear in a New Jersey courtroom Monday to face charges of vehicular homicide, assault and reckless driving.
Morgan remains in critical condition, but a rep for the former 30 Rock star told E! NewsSunday he had "been more responsive today, which is an incredibly encouraging sign."
The 45-year-old Saturday Night Live alum sustained multiple injuries, "including a broken leg, a broken femur, a broken nose and several broken ribs," said his rep, noting, "We expect him to remain in the hospital for several weeks."
Morgan, a father of four, has his family by his side as he receives "excellent care" at Robert Wood Johnson Hospital, his rep said. His fellow comics and countless celebrities have offered messages of support, prayers and love on Twitter.