Most NASCAR sponsors measure their investment in on-car advertisements in dollars and cents. Here's a story of one with far more value.

About four years ago, a young woman named Melissa Lech was struck and killed by a hit-and-run driver in suburban Chicago. Since then, her family had sought in vain for any clues about the identity of the driver.

Kevin Conway heard of Melissa's story, and agreed to put her picture and information on the rear deck lid (what, in street cars, would be the trunk) of his Nationwide car for last September's Chicagoland race. Still no word, until Sunday night.

According to ABC News, the following happened:

A stranger rang the doorbell of the home where Melissa's sister, Michelle, lives with her husband. The man, who called himself Dave, sat down at the kitchen table and confessed. He told Michelle Lech his conscience had been troubled after seeing "the NASCAR thing." He then described how he struck her sister on that August night in 2008, stopped to check that she was still alive, then got scared and drove away.

Michelle said the man neither apologized nor gave his last name, but her husband got the man's license number. One call to the detective who had been handling the case later, and the man, 27-year-old David McCarthy, was in custody.

Conway was "thrilled" to learn that the advertisement had worked, and added, "I hope this brings an element of closure so [Melissa's family] can begin the healing process."

McCarthy is being held in lieu of a $1 million bail, and is charged with causing personal injury and leaving the scene of an accident.

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