ADVANCE FOR PUBLICATION ON SATURDAY, SEPT. 4, AND THEREAFTER - Retired NYPD Officer Mark DeMarco, poses for a portrait in his home in the Staten Island borough of New York on Tuesday, Aug. 3, 2021. For a time after 9/11, He replayed the what-ifs in his mind. If he'd gone right instead of left. A bit earlier. Or later. "I couldn't figure out how I got out of there alive," he says. (AP Photo/Wong Maye-E)