Parents Driving Drunk Endanger Most Vulnerable: Their Own Children

Aug. 21, 2009 — -- It is a behavior that's hard to fathom -- parents driving drunk with their children in the car. Yet studies show that two thirds of children who die in drunken driving accidents are killed by the very people in charge of caring for them.

"Criminal behavior that puts our children at risk" is inexcusable," said Carl McDonald, a former lieutenant with the Wyoming State Highway Patrol. McDonald said he considers combating drunk driving his life's work.

"As a trooper, I was very aggressive on drunk driving, and I was proud of my ability to pick up on that," McDonald said in a recent interview in New York. "I would walk up to a car and from eight feet away on initial contact with the driver of a car, I can tell you whether or not that driver was sober or intoxicated."

But there would be one drunken driver whom McDonald did not suspect, and who changed his life forever.

"I was living my life around a woman who was intoxicated often and [I] didn't know it," said McDonald.

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The woman McDonald says he didn't suspect was his wife, Susan, a dispatcher with the sheriff's department, and the mother of their only child, Carlie.

Susan McDonald says her drinking increased over the years and, at her worst, she was a raging alcoholic.

"I'm sure I was drinking at least a fifth of whiskey a day," she told "20/20." "And I was driving."

Because of her drinking, Susan lost her job, her three-year marriage to Carl ended and, in the divorce, Carl sought and won primary custody of Carlie.

For two-and-a-half years, Susan would see Carlie on a regular basis, but then Susan's drinking escalated and, for several months, she couldn't bring herself to see her daughter, as difficult as that was for her, she said.