Clark was last seen at the Royal Ground Coffee in the 1600 block of Polk Street in San Francisco, California on July 8, 2009. He purchased a $2 cup of coffee there, paying with a credit card; that was his last known financial transaction. The employee who served him stated he appeared mentally and physically normall at the time. He has never been heard from again.

Prior to his disappearance, Clark confided to his family that he felt stressed and wanted to take a vacation, but they stated he had never traveled before without telling them where he was going. He left all his belongings behind, including his car, camping gear, passport, clothing, suitcases and cellular phone charger, items he would have taken if he was going on vacation. His family couldn't find his blue road bicycle, but they stated it's possible he sold it before his disappearance. Clark hasn't used his cellular phone since he went missing, and he didn't make any significant withdrawals from his bank accounts before his disappearance. He did not have financial problems or significant debt.

Clark worked as a registered nurse at the time of his disappearance. He is extensively traveled both within the United States and internationally, and enjoys camping, hiking, fly fishing, playing the guitar, singing, painting, drawing and sculpting. He once made a bike trip from Santa Barbara, California to Seattle, Washington, a distance of over a thousand miles. His case remains unsolved.

Above: Clark's tattoos