SAN FRANCISCO—Face grim and emotionless as if hardened by years on a special investigation force, returning rock-show attendee Paul Grasso flashed his hand stamp to the bouncer at Highfalutin’s Thursday night like a world-weary field agent displaying his dented and tarnished badge while ducking under the yellow tape at a horrific crime scene. In much the manner of jaded, laconic plainclothes detectives known as “Hawk” by the other veterans of the street crimes division, the 27-year-old first elbowed his way through a long line of people as if they were pesky but ultimately clueless tabloid reporters who persisted in obstructing official police business. The club’s employees said Grasso entered the venue in the company of his friend and college roommate Connor, who had assumed the demeanor of a grizzled partner of 20 years as the two simultaneously revealed their red stamp-pad marks. Others present to see the same jam-band festival confirm that the pair proceeded calmly and wordlessly to the bar, where they ordered Bud Light with the casual resignation of street veterans asking a flustered forensic lab technician for details on bullet-riddled victims. Grasso was later observed casing the floor for a spot with a good view of the bands in the manner of an expert incident–reconstruction analyst meticulously deciphering dark mysteries written in blood spatter.