HARTSEL, Colo. — Robert L. Dear Jr. was a man who lived off the grid.

On this lonely, snow-covered patch of land in a hamlet ringed by the Rocky Mountains, his home was a white trailer, with a forest-green four-wheeler by the front door and a modest black cross painted on one end.

As police officers surrounded it on Saturday, looking for clues to what they said had sent its owner on a shooting rampage at a Planned Parenthood center that left three dead and nine wounded, neighbors said they barely knew him, beyond one man’s memory of his handing out anti-Obama political pamphlets.

Van Wands, 58, whose wife owns a local saloon, said there were two types of people in the area: the old-timers who put effort into getting to know their neighbors, and the newcomers who wished for solitude. Mr. Dear, he said, fell solidly into the second category.