James Moran, who still wears the bristle cut of a combat infantryman, is no stranger to death. His Army outfit was almost wiped out at the Battle of the Bulge in 1944, and during 26 years as the police chief of Westfield, N.J., he dealt with his share of mayhem. But of all the ugly things he saw, the worst was the carnage on Hillside Avenue. Moran was there, one night in December 1971, when officers broke into a rambling 19-room Victorian mansion and removed the remains of the List family. The victims—Alma List, 85, her daughter-in-law Helen List, 45, and her grandchildren Patricia, 16, John Jr., 15, and Frederick, 13—had been shot, then neatly laid out side-by-side, as if the slaughter had been committed by a fussy mortician.

The one member of the family not found was the patriarch, John List; he simply disappeared. List, 46, was the prime suspect in the killings, and there were plenty of theories about why he might have done it. Shocked neighbors speculated that List, a devoutly religious man who worked as an accountant, had exploded because of mounting financial pressures and his belief that his wife's drinking was causing him to lose control of his family. Whatever the motive, no one ever located List. But even after Chief Moran retired in 1986, he kept a picture of List, a reminder that the man was still out there, somewhere.

Then, on May 21, Moran's obsession with List finally came full circle. That night, the Fox Broadcasting crime show America's Most Wanted—a program that has become a video-age substitute for post office WANTED posters—did a segment on the 18-year-old murders. Viewers were aided by a bust, created by sculptor Frank Bender, that turned out to bear a startling resemblance to the 63-year-old fugitive. Within days, 350 people phoned in tips. One caller furnished the name of Robert P. Clark and an address in Midlothian, Va. Eleven days later, FBI agents went to Maddrea, Joyner, Kirk-ham and Woody, an accounting firm near Richmond, where they found Clark, a man who looked remarkably like the bust shown on TV. Clark calmly denied that he was John List. Fingerprints indicated otherwise, and New Jersey officials began drawing up extradition papers and prepared to prosecute the case.

When John List vanished, he left behind an incriminating trail of evidence, and, say Westfield police, a detailed confession. Prior to the crimes, according to law enforcement sources, List was strapped financially. He was not working steadily and had just spent the last few thousand dollars from his mother's $200,000 savings. He could not keep up his mortgage payments. The economic troubles only added to the simmering domestic disputes. List was tormented by the belief that his wife was drinking heavily and believed his daughter was experimenting with marijuana. He also suffered from the general fear that his family was slipping away not just from him, but from God as well. In his confession, a five-page letter to his minister, List insisted that by "killing them, they would die Christians," according to Robert J. Bell, at the time Westfield's chief detective.

In hindsight, neighbors now say they saw it coming. List had always controlled the family's social life, limiting contact with acquaintances and the children's friends. Then, in October 1971, he reluctantly agreed to throw a Halloween party. The guests who drank and danced in the ballroom of the List mansion wore appropriate costumes and masks—devils and angels. Circulating among their guests, Helen List and her teenage children were caught up in the gaiety. But throughout the party List stood off to the side, dressed in a business suit—a dour presence among the celebrants.

As the police reconstructed events, days later, on Nov. 9, List cracked. He loaded a 9 mm pistol and a .22 caliber revolver. List killed his mother, an arthritic invalid, and his wife. The children were shot, one by one, as they arrived home from school. After each killing, Moran says, List mopped up the kitchen floor with paper towels.

Then, police say, List put the guns away and undertook a methodical getaway. He wrote Westfield public schools that he was taking his kids on an extended vacation to North Carolina. He canceled delivery of the mail and milk. He wrote letters to supervisors at his children's part-time jobs. Finally he abandoned his car at Kennedy Airport, apparently hoping authorities would conclude he had fled to Europe. Weeks later, after neighbors reported the light bulbs flickering off one by one, police broke in and found the bodies.

The full details of List's next 18 years remain sketchy. But from all appearances he reinvented himself as Bob Clark and quietly went back to work as an accountant in Denver. From 1979 to 1986 he was controller at All Packaging, a paper-box manufacturer outside Denver. Fellow workers recall that the man they knew as Clark was a dedicated employee who once went six years without taking a vacation. Clark joined a Lutheran congregation, helping with a car pool for shut-in church members. And at one religious gathering he met Army base PX clerk Delores Miller, now 48. They married in 1985 and shared a tiny two-bedroom condominium. Clark impressed neighbors as a devoted husband. "Once when Delores injured her hand, Bob did the cooking," says Wanda Flanery. "She'd come home from work and he had dinner waiting."

His life was not exactly an idyll, however. Clark was fired from his $500-a-week job three years ago because All Packaging was preparing to install a new computerized operations system that his bosses doubted he could master. He spent several years working part-time jobs, and the couple slid towards poverty. Finally, in February 1988 Clark landed a position in Virginia. He headed back East to find a home, and Delores soon joined him.

They settled into a blue clapboard house in a Richmond suburb. The couple lived quietly but were far from hermits; they spent holiday dinners and watched television with a neighbor. Bob went to Lutheran services, tended his garden and discussed movies and literature with friends. A patchwork heart hung on the Clarks' front door, and nearby a small sign read BLESS THIS HOUSE.

And so when Bob Clark, nice guy, was revealed to be John List, suspected mass murderer, the people around him reacted with disbelief bordering on the clichéd. Says Joseph Stefano, who lives down the street: "it's impossible for anyone to believe that he is the person who committed this crime." According to FBI agents, Delores acted as if she had no clue about her husband's past. "I hope somehow this is not true," she said. "And if it is, he was so stressed out that something snapped."

Though Chief Moran had dropped his active search for List, his colleagues in Union County law enforcement circles had not; they persuaded America's Most Wanted to look into the case. Now, with List on his way back to New Jersey to face murder charges, Moran and his pals figure their job is done. "This is the greatest thing that has ever happened to me," says Chief Moran. "This bum should never get away with this."

—Ken Gross, Margie Bonnett Sellinger in Virginia and Jack Kelley in Denver