Elvis Presley was still a young man when he went to Las Vegas in the summer of 1969. He was just 34 years old and in the physical and creative prime of his life. In the past year he had enjoyed two enormous triumphs. The previous winter, NBC had aired an acclaimed television special that reintroduced him as a concert performer after a decade spent in increasingly vapid Hollywood films. More recently he’d been to Chips Moman’s red-hot American studios, a visit that became the last great recording sessions of Elvis’s life. And yet there was still so much he hadn’t accomplished. Although there were few people in the Western world who had not heard the name Elvis Presley, he had yet to perform outside North America (and never would); in fact, he’d never staged a concert in New York City. He had given up touring for the movies while still in his 20s, during the late 1950s, when rock and roll — compared with what rock and roll became in his absence — amounted to little more than a folksy cottage industry. In Vegas, he would play what amounted to the first hour-long live concerts of his career as a modern pop star.

It is August 24, 1969, and Presley has eight years to live. " This is my first appearance in nine years live, " he says three songs into his performance, which appears more or less in its entirety as the first disc of the new four-CD set Elvis: Live in Las Vegas (RCA). " I appeared dead a few times, but this is the first time live. " He gets a laugh: little did he know how many post-mortem appearances he would be called on to make. He is three weeks into a month-long run at Kirk Kerkorian’s brand-new International Hotel, and by the end of the run he will have become Las Vegas’s all-time biggest attraction, in terms of both money grossed ($1.5 million) and total audience (over 100,000). Already, his performance at the International has been hailed as a triumphant return to form — as rock and roll’s first great second act.

It isn’t hard to hear why. He strikes you, for the first time, as a full-grown man: his feline grace and sleepy teenage sensuality have given way to a rugged, toughened animalism. He’s backed by as fine a band as he’d ever work with — after catching Elvis during this engagement, Sam Phillips said he’d never seen a better rhythm section. Guitarist James Burton, bassist Jerry Scheff, drummer Ron Tutt, and pianist Larry Muhoberac had reinvented rockabilly as a kind of ’60s-modern hybrid of honky-tonk and funky soul, and from the first notes of " Blue Suede Shoes, " they’re in attack mode. Then Elvis hums himself into key and blows the doors off the first of two Ray Charles songs in the set, a manic reading of his old favorite " I Got a Woman. "

He is loose and rambling and self-depreciating in his introductions, hinting good-naturedly that the hotel’s security goons are looking for an excuse to drag him out: " Look, look, he’s a squirrel! Git ’im! Get ’im! " If you didn’t know any better, you might assume it was the chemicals talking. In fact, the drugs wouldn’t seriously impair his performances for another three or four years. It’s just that Elvis has never let on what a goofball he is: you get the sense that he hasn’t any idea how alien his unreconstructed backwoods humor (heavy on bad puns and squirrel jokes) strikes an uninitiated audience, as it must have in the sophisticated folds of a Las Vegas showroom. In August of 1969, he is still getting used to being back on stage in front of an audience. And though he already knows how well he’s being received and is aware that his performances are among the best of his career, his nervous patter makes him sound, more than anything, as if he were scared shitless.

At one point he lulls the audience into a sense of cozy intimacy with a soft-spoken introduction; he’d been trying to come up with a special song, he says, " a message song, a song that really says something. " He makes a string of jokes at his own expense, and then without a breath of warning he screams beyond his upper register, with a jarring ferocity, " YOU AIN’T NUTHIN’ BUTTA HOUND DOG! " and the band are suddenly there behind him, double-time, and guitarist Burton unleashes a savage solo. It is over almost before you have recovered. Message received: never before has Elvis set out to startle his audience so plainly. He follows " Hound Dog " with a string of raw-throated, throbbing, fast, hard rock-and-roll numbers: " I Can’t Stop Loving You " and a rumbling " Johnny B. Goode " and " Baby, What You Want Me To Do, " an unadulterated swinging electric blues of the type he hasn’t attempted since the dawn of his career. There is a carnivorous catch in his voice, a tearing at the fabric of himself, that is unlike anything he’d done prior to his ’68 Comeback. Without pause, he jumps into a bold, surf-accented version of Del Shannon’s 1961 hit " Runaway " that might be the closest Elvis ever came to garage punk.

There’s an orchestra, and two backing vocal groups, but they lay off for most of the gig. They creep back in for an ill-advised medley of the Beatles’ " Yesterday " and " Hey Jude " that nonetheless proves Elvis’s ability to sing current pop. A better example is provided by " In the Ghetto, " his own recent hit, and a spirited, fast-paced " Suspicious Minds, " a new song that would remain a staple of his act until his death.

THE REST OF THE STORY is well known. Just four years later, Elvis was in serious trouble. In 1973, his wife left him for her karate instructor and took their daughter with her. By that time, Elvis’s drug use had reached epidemic proportions, and when he was hospitalized in October of that year for a reaction to the dozen-odd drugs he was taking regularly, it was discovered that he had chronic bowel and intestinal problems. His stage manner had become increasingly erratic; his costumery and choice of material reflected a troubling mix of mysticism, messianism, and self-pity, the material veering toward schmaltzy, heavily orchestrated inspirational ballads and maudlin European love songs. Off stage he was gripped by passing obsessions — karate, filmmaking, jets, firearms, Richard Nixon — but mostly stayed holed up in bed. By the accounts of his yes-men, he’d grown bored with Vegas after about two years. And so it is not surprising that three of the four discs that make up Elvis: Live in Las Vegas date from 1969 through 1972. The second disc is drawn from an engagement in August 1970. Disc three jumps back to his February 1970 stint at the International, where there was an emphasis on recording current pop hits and recent songs for a live album, including Neil Diamond’s " Sweet Caroline " and " Kentucky Rain, " and then tacks on some tracks from 1972, including the Beatles’ " Get Back " and his overblown set-closing " An American Trilogy. "

The latest performances on Elvis: Live in Vegas date from December of 1975; there is nothing here from his last-ever Vegas performances a year later, in the waning nights of 1976. In 1975, he is an old man: his voice is quiet and wilted, and the band reflect his lack of energy. The performances are merely lethargic, not tragic — there is nothing to suggest imminent psychosis or death, though both lurked in the wings. A little tragedy might have been called for on Live in Vegas, but the Elvis catalogue is a curious hodgepodge these days. It is possible to find, via unauthorized releases as well as sanctioned ones, almost every studio take Elvis ever committed to tape, as well as recordings of a majority of his concert performances from 1969 onward. The authorized distribution of Elvis material continues in haphazard form, filling in the blanks between his original live and studio albums with a string of " never before released performances. " By the nature of the enterprise, it’s an inexact science.

So it was, too, in the mid ’70s. It had become impossible to get Elvis into the studio, but he continued to be an enormous live draw. He was as popular as he’d ever been: his concerts continued to attract huge audiences, perhaps because so many of his fans had never had the opportunity to see him perform live. And though critics and long-time observers could tell something was drastically wrong, he was no less loved by his public than he had been at his return to performing in 1969. He was, however, in poor physical and mental health, and those around him were gravely troubled by his growing inability to tour. He was still capable of making scads of money — if only they could get him on stage.

It took a couple decades, but the problem finally worked itself out. With Elvis dead in August of 1977, a major obstacle to the exploitation of his catalogue had been removed. Fans no longer had to measure their love against the hardening image of a bloated, abusive, third-rate singer. The release schedule has picked up steadily, and though Elvis hasn’t had a chart hit since 1982, he released some of his best material in the 1990s, including the boxed sets King of Rock N Roll: The Complete ’50s Masters and From Nashville to Memphis. Elvis was under contract to deliver two new albums per year to RCA; there have been a dozen Elvis releases in 2001 so far, with two more on the way.

On August 16, 1998, the 21st anniversary of his death, Elvis began his third act, as his tour resumed in Memphis, in front of a sold-out audience. His best touring band was reassembled — including Burton, Scheff, Tutt, and pianist Glen Hardin — and Elvis was beamed in from the afterlife via video screen: thanks to multi-tracked audio and film recordings made in the 1970s, it has become possible to isolate his image and voice, so that he appears to joke with and cue the live band. He was in New England earlier this month for two nights at the Mohegun Sun casino in Connecticut — after all, he had a few albums to promote. He’d appeared here a few times live, but this was his first time dead.