Nearly 32 years ago, Sid Vicious, formerly the barely adequate but sullenly handsome replacement bassist for the Sex Pistols, woke up from a dopesick drug coma in the Chelsea Hotel and found his girlfriend, Nancy Spungen, gut-stuck and dying in the bathroom. Documentary Who Killed Nancy re-enacts the romance leading up to that sordid episode, and the circumstances of Sid’s OD mere months later. Interviews with now-middle-aged scenesters are interspersed with anime punk rockers and lurid solarised re-enactments featuring a Nancy stand-in, with anachronistic tramp-stamp tattoo, bleeding onto her lingerie. Nearly everyone agrees that Nancy was a “third-rate chick,” a slag—but after hearing one contemporary describe Sid murdering a cat, one wonders why he was considered such a catch. (Did Sid think this vile acte gratuit was, as he describes himself in one interview, “existentialist, like Jean-Paul Sartre”?) Sid’s upbringing in lowlife bohemia, with a mother whose idea of a care package was jujubes and syringes, is offered as explanation. Director Alan G. Parker, identified onscreen as “Sid’s Biographer,” finally builds a cold case for reasonable doubt that Sid murdered Nancy, but if you don’t find these rather piteous characters intrinsically interesting, he doesn’t communicate why they are. An unnecessary retelling of rock’s dingiest “legend”—ever get the feeling you’ve been cheated?