On the basis of an autopsy, Shelby County Medical Examiner O.C. Smith issued a conclusive finding Monday that the death here last month of Dr. Don C. Wiley, a renowned biochemist, was the result of an accidental fall into the Mississippi River from the Hernando DeSoto Bridge. At a press conference at Memphis police headquarters, Dr. Smith ruled out either foul play or suicide as a cause of the scientists death, which occurred in the early morning hours of November 16,. Smith said there was no pattern of injury suggesting violence and that the possibility of Dr. Wileys death having been a suicide was carefully considered and rejected. Police Director W.A. Crews said his department had been unable to determine the whereabouts of Dr. Wiley between midnight and 4 a.m., when a patrol unit making an hourly check discovered Dr. Wileys rented Mitsubishi Galant parked at curbside in a westbound lane of the bridge, keys still in the ignition. The scientist, who was attending meetings in conjunction with his membership on the St. Jude Childrens Hospital board of directors, had last been seen about midnight, leaving The Peabody downtown in the aftermath of a banquet. Dr. Wileys disappearance -- unaccounted for until his body was found last week washed ashore downstream near Concordia, Louisiana -- had occasioned widespread media interest, much of it due to the Harvard professors international reputation for his research into dangerous viruses, such as those responsible for AIDS, influenza, and Ebola. Citing damage to both the left and right sides of the Galant, Dr. Smith speculated that Dr. Wiley had grazed a road-construction divider on the driver side of the car, then swerved to curbside with enough force to displace a hubcap on the passenger side. Smith said Wiley had apparently walked to the right side of the vehicle to inspect the damage there, then somehow fell across a guardrail that was 43 inches above the roadbed, below Dr. Wileys center of gravity, as the examiner noted. Dr. Smiths judgment of accidental death was predicated on the nature of Dr. Wileys injuries. A fractured sternum, coincident with a crushed button midway down the scientists shirt, suggested to the examiner that Dr. Wiley had frontally encountered the concrete top to a box beam on the outside of the guardrail. Dr. Wileys other injuries, including contusions and a fractured neck vertebra, and fractured ribs, were consistent with the scientists impacting the river,135 feet below, on his right side. From this evidence, Dr. Smith concluded that the scientist had fallen, in that persons jumping from the bridge generally cleared the box beam, which Dr. Wiley had struck with his chest on the way down. Among the factors that might have contributed both to Dr. Wileys traffic mishap and to his subsequent fall, Dr. Smith included the following: an infrequent and poorly understood seizure disorder which was experienced by Dr. Wiley two or three times a year -- one which caused momentary disorientation but not unconsciousness; fatigue...due to the late hour and long day; and the presence of alcohol at levels suggesting impairment. Concerning the latter, Dr. Smith stressed that toxicology studies had not been concluded to a point making a judgment about alcoholic intoxication certain and that the levels of alcohol in Dr. Wileys body could be due substantially to fermentation after death coupled with diffusion from the stomach. In addition to the potential causes mentioned, Dr. Wiley pointed out the instability of the roadbed on which Dr. Wiley had stood and the further destabilizing effect of passing vehicles, especially the 18-wheelers which frequently cross the bridge in the early morning hours. Such factors may have played a role in his [Dr. Wileys] going over the rail, more so if he were also impaired or under the effects of a seizure, said Dr. Smith, who theorized that Dr. Wileys unexplained presence on the Hernando DeSoto bridge may have been due to a wrong ramp turn on an Interstate connection downtown. "He was on his way to West Memphis, and he had no reason to be in West Memphis," who, along with Directore Crews, fielded some non-medical questions at the press conference. Dr. Wiley had been staying with his father, who lives in Raleigh, reachable via Interstate 40. A right turn at the downtown connection leads to the bedroom community, while a left turn puts a motorist on a westward course, over the bridge.. The absence of significant water levels in Dr. Wileys stomach and lungs was an indication that the scientist died from the impact, not from drowning, said Dr. Smith.