THERE IS NO denying what Dennis Sweeney did. He walked out of a sleetstorm last March into the Associated Press Building in Rockefeller Plaza, took the elevator to the ninth floor and, within 20 minutes of entering the law office of Layton & Sherman, shot Allard Lowenstein dead with a Spanish pistol.

Precisely what happened during those 20 minutes is unclear. But a few things are known. Sweeney complained that Lowenstein was tormenting him with voices. Lowenstein had heard about these voices before. He knew that Sweeney, a former protege from the civil rights era, hated him. He knew that Sweeney was paranoid and convinced some mysterious forces were trying to kill him. Lowenstein tried to reason.

"You're sick, Dennis," he said. "You need a psychiatrist."

It was a fatal miscalculation. Sweeney pulled the pistol and fired seven shots. Five struck Lowenstein in the chest, stomach and left elbow. Sweeney then walked to the anteroom, placed the gun on a desk, sat down and calmly smoked a hand-rolled tobacco cigarette. He did not try to run. In the wake of panic and weeping that followed, Sweeney conducted himself with an eerie dignity. And while the great and near-great prepared eulogies to Lowenstein -- former congressman, civil rights activist, nemesis of Lyndon Baines Johnson -- Sweeney was led away to Bellevue like a sleepwalker.

During the weeks that followed, people who had known the two men as friends wracked their memories for some foreshadowing. Nearly everyone who was close to Sweeney at some time over the past 20 years had heard that he had grown reclusive and strange, haunted by voices and disembodied tormentors. The Sweeney they recalled was a perennial youth, endowed, in retrospect, with nearly mythic qualities of bravery and idealism. They could not imagine how he could have been so broken along the way, been so transformed by the years, as to arrive at Lowenstein's office one afternoon carrying a loaded pistol.

Sweeney was never one to talk about his problems. He was particularly close-mouthed when it came to his family, only alluding now and then to a sad and unsettled boyhood in Portland, Ore. His parents separated shortly after he was born in 1943, and his father, a career military man, left for England alone. He did not return for a visit until his son was two, and then stayed only one month. During that time, Dennis became so fond of his father that their parting was traumatic. He promised to send Dennis a letter from California, but no letter ever arrived. Dennis never saw his father again. In the early '50s the family received word that he had been killed in Korea.

For a time, Dennis and his mother lived with his grandparents. He was sent to a boy's ranch, where he stayed for a year and a half under the mistaken impression that he was being punished. When his mother remarried, returned to the family and was adopted by his stepfather, Jerry Sweeney. He did not want to take his stepfather's name. He did not much like Jerry Sweeney, a perfectionist who demanded in his household that hair be combed and the ashtrays emptied. At 18, Dennis was liberated by a scholarship to Stanford.

Sweeney matured rapidly, chose his friends with care, and sought out the most charismatic men on campus. Among these was Robert McAfee Brown, a professor or religion who was jailed in 1960 for taking part in a Freedom Ride. Under Brown's influence, Sweeney connected with politics and religion. He seriously considered attending seminary and becoming a minister -- not, as someone later observed, for reasons of piety, but because religion appealred to his intellectual curiosity. He also came under the sway of a gentle Quaker named Dwight Clark, who instilled in him the need to choose a calling rather than an occupation. After that, Sweeney never again thought in terms of a conventional career. He saw himself destined for more transcendent pursuits but was a little uncertain how to proceed. Until he met Lowenstein.

Lowenstein descended upon Stanford in a breathless frenzy to spend one year as visiting professor of political science. That was 1961. As was the case wherever he went, he revealed a geniu for exciting in students a passion for liberal causes. He had been president of the National Student Association 10 years before and had ties with student organizations all across the nation. To the chagrin of the Stanford administration, Lowenstein set about politicizing students. His method was the same wherever he went. He sought out leaders or prospective leaders whose influence he could use. He got them angry about social inequities, then told them what they could do about it.

Lowenstein courted the brightest, cultivated them, and drew them into his personal cadre. And among those he appointed as one of his personal lieutenants was Dennis Sweeney. Sweeney was terribly flattered, for he thought Lowenstein was "super smart." Al, he told a friend, showed you how to go out on a limb instead of clinging to the trunk. Lowenstein and Sweeney had long talks at night in Lowenstein's Stanford resident quarters. Their relationship, however, was not an exclusive one-on-one of mentor to protege. "The relationship Al had with a thousand other people. Al had a need for adulation from a whole host of admirers." Sweeney seemed content to be one of the Chosen.

Lowenstein set out an agenda of "important" projects for his followers. He was summoned to Jackson, Miss., that July by the Mississippi NAACP to help revive the faltering freedom movement. Robert Moses, the thoughful, soft-spoken leader of the Student Nonviolent Coordinating Committee (SNCC) was looking for a means to restore momentum. So he listened to Lowenstein's proposal to import hundreds, perhaps thousands of white students from Northern college campuses to work in voter registration. The prospect of opening SNCC that far to whites made many blacks uneasy. They sensed that Lowenstein saw the movement as a vehicle for his personal amibitons and that the white recruits would give him a power base. Yet SNCC was cynical enough to realize that it could use the whites to draw attention to Mississippi and late in the summer of 1963, the students began arriving. Among the first was Sweeney, who was perpetually primed for sacrifice. He became so zealously devoted to Lowenstein and Mississippi that he assumed a mythic stature among his Stanford peers. But one realized when Sweeney left to work as a volunteer in Mississippi the following summer that he would not return, that he would find his calling and slip into a stream of history.

He requested an assignment to McComb, Miss., and the fact that he received it indicates the respect he enjoyed. New recruits were never sent to McComb. It was the most dangerous assignment in the state, the place one went only if one was prepared to die. The whites were more vicious and more inclined to violence than elsewhere. Sweeney was, furthermore, one of the first whites to integrate the project there, a fact which SNCC knew was certain to draw violence upon the McComb Freedom House. The eight blacks and two whites who shared the frame home at 702 Wall St. knew they might be killed on a whim. At about four o'clock on a July morning, the Freedom House was bombed. A blast calculated at the equivalent of 17 sticks of dynamite went off six feet from Sweeney's bed. Miraculously, he suffered only a mild consussion.

During the violent Mississippi summer, blacks and whites withn SNCC clung to each other for survival. There evolved a unity -- later called the Beloved Community -- which appealed to Sweeney. He slipped easily into the grass roots SNCC culture and grew to revere Bob Moses as a saint. That reverence for Moses gradually replaced Sweeney's loyalty to Lowenstein, for as the summer wore on Moses and Lowenstein found themselves increasingly at odds, and one could not serve them both. The battle lines within the movement were drawn that summer at the 1964 Democratic National Convention in Atlantic City, where a contingent led by Moses tried to unseat the regular delegation of Mississippi Dixiecrats. He was thwarted by liberals, Lowenstein among them -- who cut a deal with the Johnson administration to leave the Dixiecrats intact and give Moses and his followers only two at-leage seats as a sop. Sweeney joined those who cursed Lowenstein and his liberals for the years of accumulated grieances.

For months after Atlantic City, Lowenstein confided in mutal friends that "Dennis is mad at me." Two years before his death, Lowenstein gave a tape-recorded interview to a SNCC historian, recalling how he and Sweeney "met under very ugly kinds of circumstances at places where he would attack me from a very personal feeling." Whether these encounters were as ugly as Lowenstein suggested is debatable. Their falling out did not appear at the time to be the result of any murderous alienation. Sweeney, looking back from the vantage point of his new radical sophistication, probably felt a little used, a little embarrassed by the memory of his own unabashed adoration. There was suspicion, even back at Stanford, that Lowenstein never dealt quite honestly in personal matters. There was an undeniable tension between Lowenstein and the young men in his following. "I know that many of us, most of us had passes made at us from Al," says a friend of both Sweeney and Lowenstein from the Stanford period. Often they weren't overt or verbal proposals "but clearly testing . . . to be offered an overnight room and to discover that there was one bed."

After the shooting, in fact, there were rumors that Lowenstein and Sweeney had fallen out as the result of a lover's quarrel. Everyone simply assumed that Lowenstein had approached Sweeney. Now, from his cell at Rikers Island, Sweeney denies that they ever had a relationship. Once while he and Lowenstein were traveling through Mississippi together, they checked into a motel. According to Sweeney, Lowenstein made a pass and Sweeney rebuffed it. Sweeney is not angry with Lowenstein, he claims. Nor does he feel any shame. It's just that Lowenstein wasn't always above board.)

Sweeney dropped out of school to become a SNCC employe at $10 a week. Tension between blacks and whites within SNCC increased. After the bombing stopped, federal money began pouring in and Sweeney argued with local leaders over how it should be spent. He felt some of them were building their own empires at the expense of the movement. He spent less time in McComb and more out in rural Amite County, where he didn't have to acknowledge so clearly that the beloved community was dissolving around him.

At this critical passage, Sweeney discovered Mary King. King, who had grown up in New York the daughter of a white Southern Methodist minister, was a photographer and had been around the movement since 1962. She worked as a photographer in the SNCC communications department. She was never an organizer. That work was considered too dangerous for women. She was one of the first feminists to protest machismo in the civil rights movement. Within SNCC, King was considered off-limits for casual sex. She had too much class to sleep around the way a lot of the younger white girls did. Sweeney first saw her at a SNCC meeting in Atlanta in September 1964. She was descending a stairway carrying her cameras. When she smiled and said, "Hello," he was so flustered he could scarcely speak. A friend recalls that he talked about Mary all day. During the weeks that followed, he arranged his schedule so it would coincide with hers. One Friday morning he brought her back to McComb and confided that he intended to marry her.

Politically, King was Sweeney's temporary salvation. She had contacts within SDS and the war movement which opened up new avenues for him. Sweeney moved out of the Freedom House sometime in March 1965, and that spring he and King became "floaters" wandering about Mississippi taking up projects here and there, but belonging nowhere. For Sweeney, that was a bitter realization. Only a year before, the movement required his sacrifice. He had been taken beyond himself, perhaps made courageous beyond his capabilities. But in the summer of 1965 the movement had no more need of him -- or any white. The militants were emerging, telling whites to go back North and organize their own communities. Sweeney and King were not purged from SNCC until December 1966. Mary, however, was cut from the payroll in a dispute over her work in the antiwar movement. After that, she and Sweeney resigned from SNCC and were married that fall in an intimate feminist ceremony. King kept her own name. Months later she told a friend that marrying was the only way either she or Dennis could muster the strength to leave Mississippi.

If anyone is in the position to recall Sweeney's frame of mind at the time he left the South, it is Mary King. Her recollection is vague, but she recalls that "it was very difficult. Everywhere you turned at SNCC meetings you would see bottles of Maalox. It didn't make us bitter. Sadness was more the feeling. As for Dennis, the emotional content of that time is a very private thing." Sweeney, she recalls, was not unusually bitter about the Mississippi experience. Nor could she recall any angry outburst about Lowenstein. For some time after they returned to Palo Alto, however, they were both listless. Sweeney, especially, appeared to one friend "bashed in." It was very soon apparent that the marriage was a mistake. In the South they had needed one another to survive, but in California the differences between them grew more pronounced. King was essentially strong-willed and tenacious. Sweeney was tending to drift. During the end of his tenure in Mississippi, he had tried to take on too many projects and couldn't seem to complete any of them. That kind of faltering was foreign to King's nature. "His lack of sense of purpose was one of the problems," King recalls "I felt kind of lost too, but I think I'm more pragmatic. It seemed self-indulgent to wallow in uncertainty. Dennis was more brooding."

King and Sweeney stayed together only about nine months. Sweeney later told someone that he came home one day and found her gone. And that was it. King stayed in Palo Alto for a while working on a filmstrip about farm workers. Then she returned East, where to the amazement of her old friends of the New Left she found a new career in the bosom of liberal politics. After a second unsuccessful marriage, she wed Dr. Peter Bourne, who enjoyed a brief tenure as drug adviser to Jimmy Carter. King herself joined the Carter administration and is now deputy director of the president's ACTION program.

If Sweeney was devastated by the failure of his marriage, he didn't grieve openly. Like a lot of other old SNCC workers, he was getting heavily into the Viet Nam war Resistance work. Early in 1967 he went to live at the Peace and Liberation Commune formed by Resistance leader David Harris and a handful of others. He became one of the principal planners and decision makers. "Dennis was always the one wilth quiet common sense," Harris recalls. "When the rest of us would go flying off into the clouds, he would bring us back down to earth."

On the surface, at least, things seemed to be falling into place for him. He was, by then, in his mid-20s, older than anyone else in the house. He was still thin, but his angular features had matured. His front teeth had been repaired in New York by a dentist who offered free care to SNCC workers. During that time, Sweeney was extraordinarily attractive to women. They found him "angelic" and "sweet." He slept with a succession of women; he generally went to their places rather than bringing them to the Resistance House. But his longest relationship was with a woman named Connie Field.

Sweeney met Field at a Resistance conference in Chicago in 1967. She was a boisterous, fun-loving woman from the East, and Sweeney brought her back to live with him at the Resistance House. That was not a happy arrangement, as Field's enthusiasm got on everyone's nerves. The fault was not entirely hers. Rodney Gage, a black musician who became Sweeney's closest friend in the house, explains: "It was almost like a fraternity. We weren't really open and receptive to women."

Field, at any rate, remained an outsider, and that increased Sweeney's own isolation. He had always had trouble slipping into the laid-back life of the commune. Sweeney was, furthermore, becoming politically disaffected. Resistance didn't offer him the all-consuming milieu of the civil rights movement, and he was bothered that the commune did not have the clarity of a single ideological line. He was irritated with Harris for spending so much time with singer Joan Baez at her luxurious home in Carmel Valley. Living off a rich and famous woman, he felt, was not proper conduct for an activist. Conversely, when Harris made the ultimate sacrifice and went to prison for refusing induction, Sweeney muttered that he had a "Jesus Christ complex." Although Sweeney had once espoused nonviolence as a political tactic in SNCC, he was not a convinced pacifist. He couldn't see the point in being a martyr. He pledged at one point to turn his draft card over to the U.S. attorney in San Francisco, but he never did. As the only surviving son of a military family, he was eligible for a deferment. And he took it.

Lowenstein, meanwhile, surfaced occasionally in the Bay area. After the 1964 elections he too had floated. He married and for a while he dropped out altogether to attend to his family's restaurant business. On one visit to Palo Alto he met with Sweeney. The two men embraced, and Lowenstein, noting his former disciple's apparently successful shift from civil rights to resistance, remarked: "You are at the center of things now, Dennis. I am not." Sweeney was flattered, but could not help feeling that Lowenstein was being ironic. By 1967 Lowenstein was back in the fray. Attacking Resistance for not working within the system, he flew hither and won mustering support for a "Dump Johnson" initiative, then made his successful run for Congress in New York's fifth district.

While Lowenstein hummed at the heart of American politics, Sweeney wavered at the fringe of radicalism. He could not see his own next political step. Organizing entailed too much drudgery and too little transcendence. Some of the Resistance, finding pure politics less and less satisfying, were turning to art. Sweeney finally truned to music. He owned an acoustic guitar and jammed occasionally with Rodney Gage and other musicians in the house. He was not particularly good, but he was so earnest that the others humored him. When they finally formed a band, they let him play rhythm guitar. The Fool, as they called themselves, went on the road in an old flatbed tuck christened "The Green Diamond." They performed their Resistance repertoire at rallies and for a time planned to ravel cross-country to Chicago for the Democratic Convention of 1968. In the end, Resistance left Chicago to SDS and the Yippies, and The Fool went on a two-month tour down the California coast to bring its political message to the people. The people were not particularly anxious to listen. In fact, they were frequently abusive. The caravan was a political dud and at the end of the summer The Fool began to fall apart. Sweeney tried to save it, but the others were weary of leading him through his songs. The severing stroke came when Gage left to become a "real" musician. Sweeney felt betrayed and never quite trusted Gage again.

Late in the fall of 1968, Sweeney left with Field for Boston. While there, as earnestly as he had turned to music, he turned to filmmaking, an area in which he was a total novice. While in California, he and field had helped edit a low-budget documentary about The Fool's summer tour. And during 1965, while floating in Amite Country, he had run across a filmmaker named Ed Pincus, who was shooting a documentary about civil rights violence in Natchez. Sweeney was intriqued and went around raising funds for this project. Four years later, in Cambridge, he found Pincus with a wonderful pile of excess rushes that would not fit into the polished film. The footage dealt with a 36-year-old black man named Panola who talked about how whites had beaten him down. Sweeney took a look at it and asked if he could edit it into a second film. Pincus agreed. Sweeney, unfortunately, had no particular talent as an editor. Pincus saw the finished version and said "can it." Only after it was heavily reworked by another editor did he allow it to be released. The artistic failure was bitter enough, but Sweeney also caught flak from local radicals who felt "Panola" was condescending and racist. That was a particularly brutal blow, since Sweeney spoke of a vague and inesplicable guilt he was feeling about his tenure in Mississippi. He was, as one friend put it, "rerunning old films in his head." Whatever his sins, real or imagined, he kept them to himself. He couldn't talk about his turmoil, and Field became frustrated. They separated for a time, then reconciled and traveled back west by motorcycle. Whitin nine months he had left her and begun his drift toward darkness.

There may be no single reason why Sweeney's behavior changed so radically. One pat rationale offered by people who knew him little or not at all is that the violence of Mississippi provoked his delusions, but it's more likely that the void following the violence was his undoing.

Field now suggests the sickness was like a virus that lay in his brain until isolation and desperation gave it the culture in which to grow. By the time he and Field separated, Sweeney's paranoia had been incubating for many years. Shards of suspicion which had accumulated in his mind derived from circumstances that were commonplace during the '60s. Everyone in McComb knew that he or she had a FBI file. Everyone at the Peace and Liberation Commune knew that the phones were being tapped. An FBI man even visited one day and was sitting in the front room when Harris got out of the shower. Most members of the Resistance dealt with this ubiquitous presence one of two ways: by considering surveillance a badge of honor, or a joke. Sweeney, however, internalized the threat. Surveillance became a sinister thing. He took it very personally. Once an FBI agent called his mother just to say he was keeping an eye on her son.

Lowenstein, it was rumored, also had ties to the CIA. As far back as 1964 stories circulated through SNCC that he was actually an agent. No one had any proof of this, but in those days anyone using as many airplane tickets as Lowenstein did was marked for suspicion. None of the New Left was really shocked in 1967 when "Ramparts" reported that the CIA had been setting the international agenda of the National Sutdent Association since 1952, one year after Lowenstein stepped down as president.

Lowenstein denied any involvement. What matters is not so much whether he was implicated, but that Sweeney felt he was. Once when Gage took note of a copy of Lowenstein's "Brutal Mandate" lying on Sweeney's desk, Sweeney shook his head in his characteristically understated way and said he thought Lowenstein had too many CIA ties.

The old Resistance crowd first caught an inkling that something was strange with Sweeney when he and Field arrived by motorcycle from the East. Sweeney got it into his head that his old friend Gage had assaulted Connie. Everyone knew that was absurd. After the split with Field, Sweeney began drifting once more. With Harris in jail, the little Resistance group began disintegrating and Sweeney became lost in the general dissolution. He took odd jobs, drove a hack, carried mail. He moved back to Portland around 1972 and gradually cut himself off from his friends. The voices began to make their subtle, insidious intrusion into his head.

Sweeney began to believe his mind was being read. He would turn on the television and be startled to find his thoughts broadcast on the evening news. He began receiving transmissions of voices, some of which he recognized, some of which he didn't. At first, Lowenstein's was not among them. During that early period of his sickness, Sweeney even visited Lowenstein and complained of some hostile third party that was monitoring his mind.

The transmission persisted, and in his frantic anxiety to stop them he began checking his body for hardware. He recalled the encounter with Lowenstein in Palo Alto and the words: "You are at the center of things now, Dennis. I am not." He became convinced Lowenstein was taunting him; that he knew about the surveillance. Sweeney even entertained the delusion that Lowenstein and whatever insidious agents he controlled had ordered the dentist who repaired his teeth to install a radio reciever in the bridgework. Sweeney tore the dental work out of his mouth. But the torment persisted.

Perhaps the culprit was an electrode in his brain. He confided this to his mother who, terrified that he might try to cut into his scalp, took him to a psychiatric hospital for observation. She tried to have him involuntarily committed, but the courts refused.

In March 1973, he wrote Leni Wildflower and Paul Potter of SDS that he was working as a dishwasher and planning to finish his last year of college at Portland State. "I'm at the lowest ebb of my life," he wrote, "because of the psychological warfare that is being made on me since about two years ago . . . I am fairly certain that I have software that I wasn't born with. I have done everything I can do to locate it and remove it. My efforts have all been failures and usually self-destructive. No doubt in the '60s I was party to some behavior that was politically irresponsible. If that incurred a social debt, then I am willing to pay it in reasonable terms (rather than endure) the bureaucratic sadism and infinite guilt which is what I see confronting me."

He was considering, he said moving to another country; someplace that might be more tolerant of a radical philosophy. But he dreaded the idea of starting over in a new culture at the age of 30. Wildflower and Potter wrote back, urging him to come live with them in San Jose, but he never responded. Instead, he traveled in search of medical help. Not psychotherapy, but surgery. He was looking for a doctor who could remove the electrode.

For a time he was an outpatient in a private clinic in Connecticut, but he left after doctors refused to open his skull. He went to France, where he thought he might find a sympathetic surgeon, but was back within a month.

He drifted and lived alone. The voices had destroyed his sexual desire. Sometimes they were benign. His mother, for instance, would come over the waves telling him, "I'm out here in Portland thinking of you." Others were more sinister. Agents of the CIA or FBI would say they were out to kill him. Sometimes they would call him "coward."

During the winter of 1975, Sweeney lived alone in an apartment in Philadelphia. The voices he heard most persistently were those of Lowenstein and Pincus. Perhaps, he thought, if he appealed directly to his tormentors they would stop. He called Lowenstein in New York. Lowenstein later told a friend that he had met Sweeney at Penn Station in Philadelphia. The encounter occurred late one night. Lowenstein entered the deserted waiting area and at first mistook the gaunt and haggard figure who stepped out to meet him for a derelict. Call off your agents, Sweeney said. Get out of my life. At that moment, Lowenstein recalled, Sweeney seemed more threatened that threatening.

Lowenstein was genuinely bewildered. "Why," he would ask friends later, "does Dennis hate me so much?" To the end he probably never understood the sad, disturbed boy behind the protege. More likely, his ego felt pangs from a discipleship gone sour. He thought Sweeney could somehow be made to see reason.

Around 1976 a story circulated through SDS that Sweeney had committed suicide. Only his mother and a few close friends knew for sure that he was still alive. But even they heard from him infrequently. Also, Pincus was uncomfortably aware of his existence. Sometime in 1976, when Dennis was working at a mattress factory in Lynn, Mass., he contacted Pincus and told him to call off the voices. Once he even visited his former associate at his home and threw a punch. (The blow as blocked by a visiting friend.) Pincus came to think of gentle Sweeney as a potentially dangerous man. He feared for himself and his family.

Sweeney, however, disappeared into Connecticut, where he became an itinerant carpenter. He had shown some aptitude for woodworking while in the South. Now it became his livelihood. He studied carpentry at a vocational school in Norwich, then moved from town to town in search of work. In 1978 he moved from Fall River to the old harbor town of Mystic, where he took up residence in a gray, three-story house, a cheerless place in which six bachelors shared a common kitchen and generally kept to themselves.

Late in the summer of 1979 he moved to nearby New London, where he rented a sunny room in a renovated barn on the estate of a deceased silk manufacturer. The landlords, Mr. and Mrs. Herman Hamilton, who lived on the premises, found Sweeney an odd and pitiable boy. They had no idea he was all of 37. He was generally quiet and kept to himself. That is why Herman Hamilton, who was outside cultivating tomato plants one summer afternoon, was startled to hear Sweeney shouting up in his room, "Who the hell do you think you are, you sonofabitch? What do think you doing here?" Sweeney then slammed his bedroom door. Hamilton asked why he moved from place to place. "I have to keep moving," he said. "I know they are following me." Mrs. Hamilton thought he meant creditors.

Sweeney was utterly alone. After one transcendent summer in the sun 16 years earlier, he had drifted into such isolation that the only thing he shared was a bathroom with a middle-aged gentleman down the hall. His old longing for a calling had been subverted into a desperate quest to stop the voices. By this time he had concluded that Lowenstein -- and to a lesser degree Pincus -- possessed the power to destroy people. Lowenstein, he was sure, had willed the murder of San Francisco Mayor George Moscone in 1978, as well as the 1979 DC-10 crash in Chicago. When a load of lumber fell on Sweeney's head during a construction accident, he attributed that also to the Lowenstein-Pincus syndicate. Sweeney had already resolved to go again to Lowenstein and beg him to stop, when his stepfather Jerry Sweeney fell dead of a heart attack on a Portalnd golf course. Sweeney drove to Bradley Field in his green pickup truck and boarded a night flight home. At the funeral he was silent, his gaze riveting and haunted. This was too much. Someone had to stop Lowenstein. The plan he devised contained a simple and chilling logic. He would confront Lowenstein and demand assurances that in the future he would leave Sweeney, his family and others alone. If he got those assurances, Sweeney intended to drive home to Oregon to live with his mother. If not, he would have to destroy his tormentor.

Sweeney returned to New London the first weekend in March and the following Monday walked several blocks to Raub's Sporting Goods Store to file an application for a pistol permit. He put a down payment on a 38-caliber Llama Especiala, a Spanish-made pistol built for seven rounds. The New London police ran a perfunctory check for criminal record and finding nothing put the application through in a little over a week. On Tuesday, March 13, Sweeney picked up the Llama and a box of 50 bullets. The following day he called the law offices of Layton & Sherman and learned that Lowenstein had not yet returned from the Kennedy campaign in Florida. Later that same afternoon, Lowenstein arrived in town and called in for his messages. He presumably called Sweeney back to set up an appointment for the following day in New York.

By the next morning, Sweeney had boxed his books and other belongings, and had boiled eggs and prepared other perishable foods to carry on the trip. That done, he backed his green pickup to the door of the barn. Then, inexplicably, at about 10 o'clock, he pulled away without loading. Perhaps he got uneasy about the weather. It was raining hard in New York. He went about running errands for a while. He stopped by a former employer's office to pick up a W-2 form. Then he dropped into the Norwich vocational school to request that his transcripts be sent to a school near Portland. He was going, he said, to live with his mother. At 11:30 a.m. he called to reconfirm the appointment with Lowenstein, then drove south on Route 95 to New York.

Precisely at 4 p.m. he walked into the Layton & Sherman office. The receptionist announced him and Lowenstein bustled out to shake hands. What happened after Lowenstein closed the office door behind them is uncertain, Sweeney, according to his own account, issued the ultimatum. Instead of humoring him, Lowenstein tried to reason. He could offer no assurances the voices would ever stop. Dennis, he said, you're sick and you need a psychiatrist. Sweeney drew his Llama from his windbreaker and emptied the magazine.

Dennis Sweeney is now living in a cell at the Men's Hospital on Riker's Island. He was moved there from Bellevue when doctors found him "delusional" and "seriously impaired." Physically, he resembles some ruined husk -- gaunt, jaw deeply lined, teeth missing. Authorities at Rikers say they have offered to have another bridge put in, but that he refuses dental care.

When the case comes to trial this fall, Sweeney's attorney Jesse Zaslav will plead his client not guilty by reason of insanity to charges of murder in the second degree. At that time Sweeney's politics and mental state will be dissected with meticulous precision.

In the meantime, Sweeney has asked for specific books from those found boxed in his New London room, among them, "The Essence of Christianity". He has asked for a tape recorder and paper to begin a memoir of his career. Mississippi seems to preoccupy him. So does Lowenstein. Sweeney recently noted the barrenness of Rikers and commented that he hoped it would help drive the voices away. If prison would end his torment, he could learn to live confined. For he still hears Lowenstein's voice and cannot really believe he is dead.