ROCKLAND, Maine — Two experts on drug use offered differing conclusions on whether a 20-year-old Spruce Head man was impaired by marijuana and amphetamine use at the time of a crash last year that killed one woman and left another with injuries for life.

The expert reports were filed in Knox County Unified Court Wednesday in the manslaughter case against Samuel Simmons. A dispositional hearing in the criminal case is scheduled for Tuesday morning before Justice William Stokes.

Simmons was driving north on Route 1 in Warren at about 7:30 a.m. on March 20, 2014, when his 1997 GMC Sierra pickup truck crossed the centerline near the intersection of Western Road and struck a southbound 2003 Subaru Forester driven by Alison Low of Warren, police reported.

Low, 38, died at the scene. Her 18-year-old son, Dustin Kimball of Warren, was seriously injured but recovered. Kimball’s girlfriend, Olivia Blachet, spent more than five months at Maine Medical Center in Portland.

Simmons was indicted in February on a charge of manslaughter and two counts of driving to endanger.

Earlier this month, Blachet, now 19, received a $5 million judgment against Simmons. He did not have motor vehicle insurance, however, and it was not made clear how that judgment might be collected.

In the latest filings in the case, the district attorney’s office presented a report to the defense from Karen Simone, director of the Northern New England Poison Center, in which she concluded that Simmons was impaired at the time of the crash. She based that conclusion on blood tests taken from Simmons after the crash.

“Based on the limited information provided, it is likely that use of marijuana and amphetamine, combined with less than optimal sleep, contributed to the inability to maintain lane position and therefore the death of the other driver. The recent use of amphetamine suggests that the driver may have been aware of impairment and made an attempt to compensate for it by taking amphetamine,” Simone stated.

But in a rebuttal report filed by defense attorney Eric “Rick” Morse of Rockland, Dr. Alan Wartenberg contends that Simmons was not impaired. Wartenberg is a physician from Attleboro, Massachusetts, with more than 30 years of experience with patients with chemical dependencies.

Simmons told police that he had last smoked half a marijuana cigarette no later than 9:30 p.m. the night before the crash and had gone to bed shortly after 10 p.m. The teen told police he used marijuana regularly to treat anxiety and insomnia, according to the report by the Massachusetts doctor.

Simmons said he had gotten seven hours of sleep and was driving to his job at a car dealership the morning of the crash. He stopped at a Dunkin’ Donuts at 6:45 a.m., although the location was not stated in the report. His last recollection before the crash was passing the Maritime Farms store on Route 1. He said he may have fallen asleep.

The doctor’s report pointed out that Simmons was examined by an officer trained in spotting impaired drivers and he did not find that Simmons was impaired. Wartenberg, who said he has testified in numerous trials in Massachusetts on the subject of impaired driving, said the marijuana level in Simmons’ blood was consistent with use no later than 9:30 p.m. the previous night.

In the civil suit filed on behalf of Blachet, the documents pointed out that the woman, who was 27 weeks pregnant at the time of the crash, suffered permanent neurological injuries as a result of the crash. The devastating injuries will take away any hope she had of a normal life as a mother, the lawsuit stated.

Low’s family has also filed a negligence lawsuit against Simmons. That case is pending in court.