RICHLAND — There might never be a conclusive answer about what caused a Pasco man to drive the wrong way on the highway, killing himself and a Tri-City couple in November.
Toxicology results recently received by the Washington State Patrol confirmed that Marco De La Mora was not under the influence of alcohol or drugs when he ended up going the wrong way on Interstate 82 near Richland, said Lt. Roger Wilbur.
"The information we received was negative, meaning there wasn't any intoxicants or drugs," Wilbur said. "It just gives us inconclusive information as to the exact reason why."
De La Mora's family has said that the 26-year-old was diabetic and might have been suffering from a medical issue that caused him to become disoriented. Wilbur said there is no test that could rule that in or out as a possibility.
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The crash occurred about 8:30 p.m. Nov. 28 near the Dallas Road exit on I-82.
De La Mora's family said he left his job at Columbia Center mall about an hour earlier because he wasn't feeling well. He was supposed to be heading home, and no one is sure why he was on I-82.
De La Mora was driving east in the westbound lanes and slammed head-on into a car driven by Heather Davidson, 27, of Richland. She and her fiance, Stephen Metzger, 30, of Kennewick, were killed. Their 3-year-old son Brennen, who was strapped into a car seat in the back seat, survived.
The state patrol's major accident investigation team still is working on completing the report for the crash.
"There's a lot of areas for speculation -- visibility was poor, it was foggy, he got disoriented -- but I don't know if we'll ever ... be able to answer why that person was on the wrong side of the road," Wilbur said. "In this instance, saying (fog) was the entire result would be speculation."
It's not unusual for drivers to make wrong decisions in the fog and get disoriented, Wilbur said, adding that is why they advise motorists to stay out of the left lane of travel because that is likely the lane a wrong-way driver would be in.
Investigators also might never know where De La Mora got onto the highway the wrong way, Wilbur said. There aren't a lot of witnesses who saw him, possibly because it was foggy and other motorists couldn't see him or because people tend to stay off the road in weather like that.
"We've gone down about every path we can think of trying to get information," Wilbur said. "In this instance, it's going to be hard to hang your hat on any one thing."
* Paula Horton: 509-582-1556; firstname.lastname@example.org