After nearly a month-long search for a missing 93-year-old man that included an Oakland helicopter swooping over Nicasio, a San Rafael patrol boat scanning the Marin coastline, another boat searching the Corte Madera Creek and a search and rescue team retracing the steps of Robert Leslie Davis, the man’s car was found wrecked and abandoned at the bottom of a slope north of Dogtown on Tuesday. No one had seen any sign of Mr. Davis…