One of the show’s lessons is that you don’t have to be brilliant to get away with a crime. Illustration by Peter Strain; Reference: Pat Sullivan / AP

In “The Jinx,” a six-episode HBO documentary series, the director Andrew Jarecki investigates Robert Durst, multiple-murder suspect, Manhattan real-estate scion, and shark-eyed master of the throwaway epigram, emerging with evidence that might actually put him in jail. This isn’t the first time Jarecki has suggested that Durst might be guilty: in 2010, he directed “All Good Things,” a feature, in which Ryan Gosling commits every bad act that Durst has been accused of, plus a few bonus ones, like the implied bludgeoning of a lovable husky. “All Good Things” wasn’t much good, maybe because it was inspired by the facts of Durst’s life, few of which seem plausible as fiction. This is a man, after all, who, long after the mysterious disappearance of his first wife, Kathie, fled to Galveston, Texas, disguised himself as a mute woman, and then, while out on bail for the murder of a neighbor—whose corpse Durst dismembered with a bow saw—was arrested for shoplifting a chicken-salad sandwich at a Wegmans. (At the time, Durst had thirty-eight thousand dollars in his car.)

But if “All Good Things” got a thirty-two-per-cent rating on Rotten Tomatoes, it impressed the one critic who counted. Upon its début, Durst—who was independently wealthy, out of prison, and in no clear need of further publicity—contacted Jarecki and agreed to be interviewed. I haven’t seen the finale of “The Jinx,” so you’ll have to discern for yourself whether this decision was worth it for Durst. For Jarecki, it paid off in spades. “The Jinx” is wickedly entertaining: funny, morbid, and sad, at once exploitative and high-minded, a moral lasagna of questionable aesthetic choices (including reconstructions of ghastly events) and riveting interviews (of Durst, but also of other eccentrics, like his chain-smoking-hot second wife). The series acts as an extension of the legal process and as a type of investigative journalism. For viewers, however, it’s primarily a noir striptease, flashing revelations one by one—a method with proven appeal to viewers who like to feel both smart and titillated. Guilty as charged.

Clearly, I’m not alone, judging by the smash success of “Serial,” a podcast hosted by N.P.R.’s Sarah Koenig, which examined the case of Adnan Syed, who was convicted, in 2000, of the murder of his ex-girlfriend. The creators of “Serial” were, in turn, inspired by “The Staircase,” from 2004, an eight-part TV series about the trial of the novelist Michael Peterson, who was accused of killing his wife; it was filmed by the French director Jean-Xavier de Lestrade, who added a two-hour addendum in 2012. In the past several decades, true-crime documentaries have emerged as a kind of secondary appeals system, among them Errol Morris’s “The Thin Blue Line”; the three “Paradise Lost” movies; and the damning “Deliver Us from Evil,” in which Amy Berg got a pedophile priest to confess. The first two got their subjects out of prison; the second helped put the priest back in.

These projects have an afterlife online, where amateur detectives reinvestigate both the crimes and the documentaries themselves. Look up “The Staircase” and you’ll discover critiques of its filmmaker’s bias and, also, strangely convincing theories suggesting that an owl killed Michael Peterson’s wife. “Serial,” too, had its critics, but part of the appeal of the podcast was its transparency: Koenig placed her anxieties center stage, even when this risked making her appear credulous or uncool. Jarecki, who wears a goatee so sketchy that it might as well be another suspect, could easily seem like a questionable figure, given his slick ability to plug his films as studies in ambiguity (his others include “Capturing the Friedmans” and “Catfish,” which he produced). He’s a showman, for sure, but he wins our trust with a few wise choices, among them folding in enough material about two victims—Kathie and Susan Berman, an old friend of Durst’s, who was shot execution style in Los Angeles—that they become more than chalk outlines. Yet, perhaps inevitably, the most watchable participants are the bad apples.

This is particularly true of Durst. He’s an indelible character, mesmerizing in his strangeness: he’s parchment-skinned, blinky-eyed, lizardlike, but he has a quality of fragility, too, along with a disarming, if often peevish, directness. When he feels misunderstood, a Larry David-like querulousness creeps into his voice. He answers questions about whether he hit Kathie (yes, he did—but, hey, it was the seventies) with a candor that no sane or diplomatic individual would use. Maddeningly, this makes him seem open, even when he’s almost certainly lying. Much of the pleasure of watching “The Jinx” is simply being immersed in the stubborn illogic of Durst’s world view, which is often less cagey than surreal. Asked why he lied to the police about his behavior on the night that Kathie disappeared, Durst explains that he thought that if he offered up a false alibi (one easily exposed) he’d be left alone. Then again, he wasn’t wrong: one of the lessons of “The Jinx” is that you don’t need to be a brilliant criminal to get away with a terrible crime. You just need a cop who never follows up, plus the money for a legal team that’s savvy enough to play to the sensibilities of a Texas jury.

There is, of course, a queasy undercurrent to any show like this: we’re shivering at someone else’s grief, giggling at someone else’s crazy. Many of the best documentaries have this ugly edge, which may be why we cling to the idea that their creators (or, at least, those not named Werner Herzog) are as devoted to truth as to voyeurism. (Documentarians don’t get paid enough to do it for the money.) Yet it’s impossible not to laugh at the camp solemnity of this speech, from a Galveston detective: “Nobody deserves to be killed. Their head cut off. Their arms cut off. Their legs cut off. And packaged up. Like garbage.” When asked whether he purposely shaved his eyebrows while on the run, Durst’s response is impeccable as both humor and logic: “How do you accidentally shave your eyebrows?” At times, the moral of “The Jinx” seems to be that an air of dry wit, however inappropriately leveraged, is likely to win you allies.

It’s illuminating to compare the methods of “All Good Things” with those of “The Jinx”: both show footage of Durst as a happy child, swimming with his mother, and the adult Durst saying, “She died a violent death.” In “The Jinx,” the footage is wrenching because it’s real: the voice-over is audio from the Texas trial, played over grainy home movies. Then these images (scored with eerie singing saw) segue into an explicitly reconstructed flashback, which shows Durst’s mother’s suicide: a grotesque image, jolting the viewer with its tackiness. The transition was unsettling enough to make me wonder whether those home movies, too, were a reconstruction. At the same time, there was something useful about the coarseness, which was Jarecki’s own “tell.” It was a reminder that everything in a documentary is contrived, even one with a fancy HBO imprimatur. The most sincere people still know that they’re talking to a camera.

Against this Barnum-like theatricality, spontaneous gestures stand out. There’s a poignant scene in which Durst is found not guilty of his neighbor’s murder: he turns to his lawyer and says, uncertain, “Did they say ‘not’?” The most unsettling example comes in the fourth episode, when Jarecki suggests that he and Durst take a break from discussing his testimony in Texas. Durst has confirmed that his lawyers hinted that he could answer specific questions about the dismemberment with “I don’t know”; that way, he’d sound less coldhearted. As soon as the filmmaker leaves the room, Durst, who is still wired for audio, lowers his head and mutters a sentence to himself. “I did not knowingly, purposely lie,” he says, and then pauses, considering, to add a word: “I did not knowingly, purposely, intentionally lie. I did make mistakes.”

Durst was rehearsing the interview, the way one might rehearse one’s testimony—but does that make him seem more guilty or just more realistic about documentaries? His lawyer tells him that his microphone is hot. Durst is fascinatingly unconcerned. He says again, “I never intentionally, purposefully lied. I made mistakes.” Then, with the shrug of an honest man, he adds what might be the tagline for the series: “I did not tell the whole truth. Nobody tells the whole truth.” ♦