In the end, the unfathomable question was “Why?” And Charles Stuart, the only person who knew, had chosen to go to his grave without providing an answer. More than two months before, he had horrified the nation, and left a city in shock, with an appalling tale of urban violence: On the night of Oct 23, as he and his wife, Carol, left a birthing class at Boston’s Brigham and Women’s Hospital, Stuart said a black gunman had forced his way into their car and made him drive to the vicinity of the Mission Hill district. After demanding the couple’s cash and jewelry, said Stuart the intruder had shot Carol, who was seven months pregnant, through the back of the head, then seriously wounded Charles in the abdomen, leaving him to call state police for help on his car phone as his wife lay dying beside him. The whole gruesome scene, including the dramatic tape of rescue efforts by police and paramedics, stirred a volatile mixture of grief, fear and outrage. To the press, police and much of the public, Charles became both hero and victim, and his tragedy a paradigm of society’s battle between decency and decline.

But then it all began to unravel. By the morning of Jan. 4, Stuart found himself under suspicion, recast as villain and murderer by the testimony of his own brother. Now, with authorities closing in to arrest him, he parked his new Nissan Maxima on the Tobin Bridge leading from Boston to neighboring Chelsea. On the passenger’s seat he left his driver’s license and a terse note declaring that “the allegations have taken all my strength.” Then he jumped 145 feet to his death in the muddy Mystic River below.

The suicidal plunge from Boston’s highest span signaled another stunning turn in an already remarkable case. No longer were the Stuarts—Carol, 30, an attorney for a publishing house, and Charles, 30, a handsome businessman known as Chuck—mythologized as the perfect couple; nor was their son, Christopher, who died 17 days after an emergency cesarean, seen as the victim of a random interracial assault The story that emerged to replace Chuck Stuart’s fiction was even more sinister—a scheme of murder and deceit concocted by a coldblooded psychopath. According to investigators, Stuart not only killed his wife, but apparently used his brother Matthew, 23, to help hide the evidence. And though it seems that at first only Matthew and another brother, Michael, shared Chuck’s secret, others in the Stuart family later fell under a cloud, suspected of protecting a murderer. “This is just mind-boggling,” Carol’s older brother, Carl DiMaiti, told a Boston television station, “that they could sit with us, or allow us to visit Chuck, knowing that Chuck was responsible for what happened to Carol. It’s just unbelievable.”

Nowhere was outrage more palpable than in Boston’s besieged black community. Immediately after the Mission Hill murder, Mayor Raymond Flynn had ordered “every available detective” onto the case. Police poured into the area and carried out “stop and frisk” searches of scores of young black males. Nineteen days later the dragnet snared one William “Willie” Bennett, 39, who had been charged with burglarizing a video store. He had reportedly been seen with a gun and some jewelry in Mission Hill around the time of the murder and allegedly boasted of killing Carol Stuart. But in a police lineup, Stuart would only identify him as looking “most like” the assailant. Still, Bennett became the prime suspect, and only hours before Stuart’s suicide prosecutors were presenting evidence to a grand jury to indict him.

To many blacks, the whole affair smacked of racism. City Councilman David Scondras, among others, demanded to know why police had not taken “more than a cursory look at Stuart’s role in the killing. We have to have the same level of skepticism for all people in regard to crime, and the same level of compassion for all victims, no matter what their skin color or where they live.”

Certainly some of the anger was justified. As early as the first week of December, Boston was swirling with vague but persistent rumors that Stuart had murdered his wife. Police received dozens of calls, but failed to turn up corroborating evidence. According to the Boston Globe, police received a tip in November that a man in Lowell, Mass., had told friends that Stuart, whom he knew, had asked him how he might be able to get rid of his wife. But when investigators confronted the man, he reportedly denied that the conversation had ever taken place.

As prosecutors continued stitching together their case against Willie Bennett, another struggle was apparently being played out in the mind and heart of Stuart’s brother Matthew. Soon after the killing, Matthew had flown to California, where he remained for six weeks while Chuck was recuperating. But on the evening of Jan. 3, Matthew went to Boston Police Headquarters and for the next six hours told his extraordinary story—that on the night of the murder he had rendezvoused on a deserted street in Mission Hill with Chuck, who had passed him Carol’s Gucci purse and a nickel-plated, snub-nosed .38 revolver. Matthew said that he and a friend, John McMahon, then dumped the incriminating evidence from a railroad trestle over the Pines River in Revere—everything except Carol’s supposedly stolen engagement ring, which he had kept for 72 days before turning it over to authorities.

Matthew reportedly denied he had known that Chuck intended to murder Carol. What, then, did he think his brother had in mind? Amid sketchy press accounts and the lack of a definitive police version of events, it is hard to say. According to the Globe, Chuck had lured Matthew to Mission Hill with talk of a scam to make money. Other sources say that Chuck told his brother he planned to fake being robbed of cash from Kakas & Sons, the chic Back Bay furrier where he worked as general manager, then drop the loot for Matthew at a prearranged spot. Still another report was that Chuck had proposed a scheme for staging a theft of Carol’s jewelry in order to collect the insurance.

In any case, Matthew eventually decided to come forward. His lawyer, John J. Perenyi, said that Matthew, who works as a paint mixer, had been appalled that an innocent man—Bennett—might be convicted of murder. “The lineup pushed Matthew over the brink,” said Perenyi. “He agonized over it for a longtime.”

With Matthew’s admission, authorities began to move in on Chuck. Reading Detective David Saunders and his partner staked out the Stuarts’ split-level home in suburban Reading, but doubted that Chuck would be taken alive. “We had a gut feeling he was going to kill himself,” says Saunders. Indeed, Stuart, who had apparently been tipped off that the police were after him, spent Wednesday night at a motel in the southern suburb of Brain-tree. Early the next morning he drove to the Tobin Bridge for his final reckoning.

After Stuart’s death, authorities were pursuing a host of possible motives for Carol’s murder. According to one source, police believe he may have taken out some $600,000 in insurance policies on Carol’s life, though he cashed only $82,000 worth; investigators believe that Chuck, an accomplished chef, wanted the money to open his own restaurant. And as authorities began turning Stuart’s life upside down, something else fell out: an attractive young woman. While Stuart was recuperating in Boston City Hospital, Deborah Allen, a 22-year-old graduate student at Babson College, used his telephone charge card to make numerous calls to him. Then last week, the Lowell man reportedly approached by Chuck about killing his wife changed his story again. He publicly confirmed that the conversation had taken place. He also said Chuck told him that he wanted Carol killed because she had refused to have an abortion and he feared that with a child she might give up her job—and income—thus foiling his dreams of opening a restaurant. And, he added, Chuck complained that Carol seemed to be gaining the upper hand in the relationship.

Police sources at first suspected that Allen, a Brown University graduate who met Stuart while working summers at Kakas & Sons, had been romantically involved with him. But authorities now believe that Chuck’s affections may have been unrequited. And Allen’s lawyer insisted that she and her boyfriend were simply acquaintances of Chuck’s. “I have no idea what [Chuck] thought,” said attorney Thomas E. Dwyer. “I have no idea what he said to his pals.”

How was Stuart able to avoid suspicion for so long? Partly because he realized the usefulness of playing on whites’ racial fears. “Stuart knew that if his crime was committed in this community it would be many moons—if ever—before attention focused elsewhere,” says Massachusetts State Sen. William Owens, who represents the Mission Hill and Roxbury districts. Stuart’s credibility was also enhanced by the seriousness of his wound, which required seven hours of life-threatening surgery. “To turn the gun and shoot yourself there?” says Dan Hickey, one of the paramedics who treated Stuart at the scene. “Why not in the arm, leg or shoulder?”

Moreover, before the crime, Stuart had succeeded in going about his business as if nothing were amiss. A few days before the murder he dropped by Ye Olde Driftwood, the restaurant where he and Carol first met some 10 years before while he worked as a cook and she waitressed to help pay for school. He wanted to confirm their reservations for a Halloween party. “Chuck sat there, at table 2, talking about how excited they were about coming,” recalls one of the owners, Jim Hogan. “And all the time he knew she wasn’t going to make Halloween here. She was going to be dead.” Nor did Chuck’s performance waver after the killing. In a much-publicized gesture, hours before his son, Christopher, died, he asked to be wheeled beside the incubator to say goodbye. “For him to go and visit that baby?” asks Hogan in bitter amazement. “How? It’s like a hit-man mentality.”

No one professed understanding, and Chuck’s oldest friends were dumbfounded. “Out of all my friends this guy would never be the one I thought would do something like this,” says Tom Kelley, who had known Stuart since they were students together at a vocational school north of Boston. The shock was especially deep among those who had known Chuck and his three brothers when they were growing up in the blue-collar town of Revere. “Chuckie was the kind of son I was hoping my son would grow up to be,” says Patricia Lescovitz, whose family lived across the street from the Stuarts. “My kids loved having the Stuart boys baby-sit because they always had such a good time playing. And I never paid those boys a dime, because they would never take it.”

What wrinkles did appear in Chuck’s personality seemed harmless. Boyhood friends remembered him as intensely ambitious, and after his death it turned out he had for years been lying to some people about his education. He claimed to have gone to Brown on a football scholarship, when in fact he had attended Salem State College, and only for a few months.

Like Chuck, Carol came from a middle-class background, the second child of Evelyn and Giusto DiMaiti. A native of Medford, she was an excellent student who graduated from Boston College and cum laude from Suffolk Law School. Friends considered the vivacious Carol the perfect complement to the more reserved Chuck, whom she married in 1985. There were some signs of discord in their relationship, but nothing remarkable. Neighbor Maureen Vajdic says that not long before the murder, on a Saturday morning stroll, Carol had complained to her that Chuck had stayed out late the night before, as he did most Fridays, drinking and carousing with friends. When she confronted him, the ensuing quarrel became so loud that Chuck had shut the house windows. “She said that here she was pregnant, sitting at home alone, and he was out partying,” recalls Maureen. “She told him she wouldn’t put up with it any more.”

Yet there was nothing in the relationship to suggest murderous hatred. The news of Chuck’s guilt and his suicide devastated his parents. “I can’t talk about it,” said his father, Charles Sr., a retired insurance salesman, at his home. “It’s too sad of a thing. I don’t think I’ll ever be able to talk about it. We all hurt.” But the case also put the family in an awkward position. Within days of the murder, Matthew, who is said to have idolized Chuck, reportedly told his brother Mike, 27, a Revere fire fighter, of Chuck’s involvement in Carol’s killing. And some sources said that Chuck had sent either Mike or Matthew, along with Shelley Yandoli, one of his two half-sisters, to bring potentially incriminating insurance papers from his home to the hospital. Investigators say all but one of his siblings may have known of Chuck’s involvement before Matthew came forward.

Yet even if the siblings tried to protect Chuck, it may be that neither Matthew nor any of his blood relatives can be prosecuted. Under Massachusetts law, such kin cannot be charged for concealing evidence—or even destroying it—if they had no prior knowledge of a crime. Ironically, Matthew’s friend John McMahon could face charges if it can be proved he was aware of the murder and participated in getting rid of the gun.

Though Willie Bennett has been cleared of any involvement in the Stuart case, he and his family angrily maintain that no words of apology will undo their suffering. “I’ll never forget this,” says Bennett’s 18-year-old daughter, Nicole. “Do you know what it feels like to be home watching television and see my grandmother’s house on TV and police searching it?” All across Boston, government officials, the media and many ordinary citizens had already begun their own soul-searching over the episode. “Public officials have to decide they won’t follow the same old patterns and fall into the same old stereotypes,” says Louis Elisa, president of the NAACP’s Boston chapter. “The moral leadership has to start at the top, and hopefully society will catch up in time.”

For Carol’s anguished family and friends, the issues are more personal. What they want, above all, is a full accounting of what happened. Meanwhile, investigators continue to pursue a variety of leads. The .38 snubnose that Matthew tossed into the river was recovered last week and sent to the FBI in Washington, D.C., for ballistic and forensic tests, which may or may not shed any light on whether Chuck pulled the trigger. Authorities also reportedly ordered genetic tests to determine whether Christopher was in fact Chuck’s child. (Although preliminary examinations showed the two had the same blood type, which differed from Carol’s, an autopsy on Chuck reportedly revealed he had no sperm—a condition that may have resulted from his gunshot wound.)

Ultimately, of course, the real mystery is how any man—for any reason—could kill his pregnant wife so dispassionately. Those who knew Chuck Stuart are left groping for answers. Reading neighbor John Vajdic remembers when his wife, Maureen, accompanied Chuck on the day he returned home from the hospital. They were greeted by the Stuarts’ two black Labradors, Max and Midnight, who had been Carol’s pride and joy. “I’d have thought they would be excited to see him, but no, they just looked at Chuck and turned away,” says Vajdic. “Dogs are sometimes the best judge of character.”

—Bill Hewitt, Dirk Mathison, S. Avery Brown, Gayle Verner, Stephen Sawicki and Sue Carswell in Boston