Diane Schuler is dead, so we can't ask her what happened the morning of July 26. What's left behind is the physical evidence of a head-on collision that killed eight people on a suburban parkway in New York.

Police said 36-year-old Schuler drove the wrong way on the highway for two miles before colliding with a sport utility vehicle, killing three occupants. The other victims included Schuler, her 2-year-old daughter and three nieces. Her 5-year-old son survived. Friends and family describe Schuler as a responsible and trusted caregiver. She never would have put any child at risk, they said.

But physical evidence says Schuler's blood-alcohol level was 0.19, more than twice the legal limit of 0.08. Six grams of undigested alcohol was found in her stomach. Medical examiners also detected high levels of tetrahydrocannabinol or THC, the main ingredient in marijuana, state police said. A broken vodka bottle was found in her crashed minivan.

Her husband insists that Schuler's erratic driving was the result of a medical condition. According to a family attorney, Schuler had an abscessed tooth, possible diabetes and a lump in her leg that was moving.

Her husband says, "She didn't drink. She wasn't an alcoholic."

"She was never drunk since the day I met her. … She was not a drinker," said Daniel Schuler during a press conference.

How then, does he reconcile such a high blood-alcohol level at 9:30 a.m.? Or the THC in her system?

If we take the most charitable view of these events, it is not beyond the pale that a stroke or a diabetic event could cause Schuler to lose control of her car.

But who can walk around with an abscessed tooth for two weeks and not seek care? One of my colleagues has suffered a good part of the summer with such a problem. His dentist, among other treatments, prescribed antibiotics to treat the infection and Lortab to manage the constant, throbbing ache.

If someone didn't have access to dental care — or bother to seek medical or dental care — he or she might attempt to self-medicate, particularly when the pain is so debilitating.

Or the other possibility exists that Schuler was an alcoholic and she, as so many addicts are adept at doing, hid her addiction from those closest to her.