Before he embarked Thursday afternoon on the deadliest workplace shooting in U.S. history, before he killed himself that night, Mark Orrin Barton sat down at his home computer in suburban Stockbridge just before dawn.

"I have been dying since October. I wake up at night so afraid, so terrified that I couldn't be that afraid while awake," he typed in the letter police later found in plain view on a living room coffee table. "It has taken its toll. I have come to hate this life and this system of things. I have come to have no hope." He would live, he wrote, only long enough "to kill as many of the people that greedily sought my destruction."

As he wrote the letter, Barton, 44, already had killed his second wife, Leigh Ann, 27, on Tuesday, hiding her body in a closet in the two-bedroom apartment they shared. On Wednesday, he had slain his two children from his first marriage, Matthew David, 11, and Mychelle Elizabeth, 8, and tucked their bodies into their twin beds.

He had struck all of them, he wrote, "with a hammer in their sleep and then put them face down in the bathtub to make sure they did not wake up in pain." He had placed a stuffed animal next to his daughter's body, a Game Boy video next to his son's.

As police and people who knew Barton try to fathom what drove him to kill his family and nine office workers in Atlanta, it is this blend of personal torment and reverence for the trappings of suburban domestic life that seems so haunting.

Barton had twice constructed a veneer of normalcy, with two different wives -- both now killed -- in two separate Georgia communities and in two distinct careers. A churchgoing man who sometimes taught Sunday school. A 6-foot-4 Boy Scout leader. A father who canceled appointments to take his children to soccer games, recalled Robert Hughes, an attorney who knew him.

Yet something else churned not far beneath the surface.

Before his first wife, Debra, and her mother were bludgeoned to death on a camping trip six years ago -- a crime that has never been solved but for which investigators have long viewed Barton as the prime suspect -- Debra Barton had confided to her diary about the uneasiness she felt.

She filled pages describing her love for her husband, her joy at watching him with their children. But she also wrote of watching her husband as he mowed the lawn, hoping that he would not come inside so that she wouldn't have to see his "rage," recalled Edward Tanner, an attorney who saw excerpts from the diary while representing Barton in a fraud case involving a $600,000 life insurance policy that Barton took out on his first wife just before her death.

Barton referred to that death in the note he left at his apartment this week, taking special care to deny that he was involved in the slayings of his first wife and her mother, Eloise Spivey. "There may be similarities between these deaths and the death of my first wife," Barton said in the letter. "However, I deny killing her and her mother. There's no reason for me to lie now."

At a news conference today, Henry County Police Chief Jimmy Mercer became noticeably emotional, halting to compose himself as he read aloud three additional brief, handwritten notes that lay loose beside the bodies of the second wife, Leigh Ann Barton, and the two children. "I give you Matthew David Barton," one note said, which seemed -- like the others -- directed at God. "My son, my buddy, my life. Please take care of him."

He described Leigh Ann as "my honey, my precious love," even though she reportedly had decided to end their marriage. He killed her, he wrote, "because she was one of the main reasons for my demise as I planned to kill the others. I really wish I hadn't killed her now. She really couldn't help it and I love her so much anyway.

The letter referred twice to "Jehovah," reflecting what acquaintances and a relative described as Barton's recent attraction to the Jehovah's Witnesses and decision to leave his Baptist church.

Today, fresh details about Barton's shooting rampage came to light.

One of the three people named in the note as apparent contacts -- along with his mother and the father of his first wife -- was a general practice attorney, Joseph H. Fowler, of suburban Atlanta, who issued a statement today saying that he had handled Barton's will and estate planning.

In an interview tonight, Fowler said Barton had come to his office Monday to discuss "routine will and estate issues," and returned again Thursday morning, dressed casually in shorts, to request additional changes to his estate.

"There was nothing unusual about him" that morning, Fowler said. "Nothing that would make you suspect that he had planned or committed wrongful acts."

Just before 3 p.m. that same day, Barton arrived at two stock market day-trading firms in the affluent Buckhead neighborhood. Witnesses at Momentum Securities Inc., the first firm Barton visited, told police that he had commented "that it was a bad trading day, and something to the effect that it was going to get worse. But he was not excited and they were not necessarily frightened of him," said Atlanta Police Chief Beverly Harvard.

Barton was at Momentum to discuss a problem with his account, Beverly said, for about a half-hour before opening fire, leaving four people dead. Then he crossed a busy street to the All-Tech Investment Group, where five others were slain. Investigators were still trying to determine today if Barton had had any relationships with the dead -- eight men and one woman -- or had fired about 40 shots at random.

Barton eluded police until shortly before 8 p.m., when he was spotted in his green Ford minivan by a Cobb County police officer in a gas station parking lot north of Atlanta, some 20 miles from Buckhead. When police surrounded the van, Barton turned the gun on himself, dying instantly.

After Barton's suicide, investigators found in his minivan a duffel bag stuffed with 200 rounds of ammunition and the two handguns used in the shootings -- a 9mm Glock that Barton had purchased in November 1993 and was legally registered to him, and a Colt .45-caliber handgun that was not, according to the Bureau of Alcohol, Tobacco and Firearms.

Two other handguns also were in the duffel bag -- a .22-caliber H & R revolver, purchased in 1976 by Barton at a South Carolina pawnshop, and a .25-caliber Raven semiautomatic pistol, purchased in 1991 from a pawnshop in Georgia by someone other than Barton, ATF officials said. Investigators are trying to determine how Barton came to possess the Colt .45, purchased in 1983 from a gun dealer in Richardson, Tex., by another person, whom ATF would not name.

In the note at his apartment, written on personal stationery and addressed "To Whom It May Concern," Barton foreshadowed further bloodshed. His last sentence was: "You should kill me if you can."

He also hinted, opaquely, at deep-seated problems within his family, writing that "the fears of the father are transferred to the son. It was from my father to me, and from me to my son. He already had it. And now to be left alone, I had to take him with me."

Acquaintances reached today could shed no light on the relationship between Barton and his father. And there is little on the surface of Barton's childhood to suggest a basis for his torment.

An only child, Barton grew up in a quiet, established neighborhood of Sumter, S.C., a city of 45,000 in the southeastern part of the state. His father was stationed at Shaw Air Force Base, about 15 minutes from the house on Wren Street where his mother still lives. His mother always struck neighbors as especially religious and still works as secretary of St. John's United Methodist Church.

In recent years, according to several of his mother's neighbors, Barton had not returned often, although he sometimes made summertime visits with his two children and attended his father's funeral in September 1997.

In high school and college, Barton appears to have made a mild impression. In the Sumter High School yearbook for 1973, the year he graduated, Barton's photograph is missing from the senior class. He is not listed as having belonged to any school clubs, and the only information next to his name is that he was a semifinalist for a National Merit Scholarship.

Today, reporters at the Item, the daily newspaper in Sumter, contacted about two dozen high school classmates, including a woman who has organized reunions. "No one remembers him," a reporter there said.

In the fall of 1975, he entered the Sumter campus of the University of South Carolina, a two-year branch of the state's public university system. Two years later, he transferred to the main campus in Columbia, where he graduated in the spring of 1979 with a bachelor's degree in chemistry.

A campus spokesman said his picture did not appear in any of the yearbooks during his time there.

Barton married his first wife in 1979. A decade later, the couple moved to Texas so he could take a job at a chemical company. According to the Dallas Morning News, Barton was fired from his job as general manager for TLC Manufacturing Inc. in Texarkana in 1990 and subsequently was charged with burglarizing the company. The charges were dropped, and Barton moved the family back to Georgia.

They lived first with his wife's parents in rural Lithia Springs, west of Atlanta. The next year, Barton moved his family to their own house about a half-mile away. They often saw her parents, William and Eloise Spivey.

Neighbors recall nothing special; the family kept to themselves, but that did not seem unusual in a neighborhood where every house has its own satellite dish and front doors are hidden by groves of maple. Barton, dressed in Docker's and polo shirt, liked to hit golf balls in the front yard. He was not especially friendly, they said, but wouldn't mind a quick chat.

Barton was a salesman for a chemical company in Macon, where he met and began an affair with Leigh Ann Lang -- who would become his second wife -- while both were married.

Publicity over the murder of his first wife and her mother got him fired from his job, and for a while he seemed to struggle with money. But he found another job within a year, said Hughes, one of the attorneys on the life insurance fraud case, which ultimately was settled.

In 1994 the family moved to a smaller, more suburban house in Morrow, just south of Atlanta. By now Barton was spending more time as a day trader, and both his second marriage and his finances were faltering. E.J. Vandiver, Leigh Ann Barton's father, said a family member told him Barton had argued with his daughter Tuesday night. "There was an argument about money," Vandiver said in an interview.

There were other pressures, too. Vandiver said the couple had fought about Mark's recent insistence that Leigh Ann become a Jehovah's Witness, which she refused to do. And she worried about her husband's day-trading. "This stock market thing -- he got so he wouldn't work," Vandiver said of his son-in-law.

By this week, Barton's resentment exploded in two brokerage offices and his own home.

In addition to his family, Barton's victims were Russell Brown, 42; Dean Dellawalla, 52; Joseph J. Dessert, 60; Tamshid Havash, 45; Vadewattee Muralidhara, 44; Edward Quinn, 58; Charles Tenenbaum, 48; Scott Webb, 30; and Kevin Dial, 38, the son of former NFL wide receiver Buddy Dial.

Staff writers Barbara Vobejda and Michael A. Fletcher and research editor Margot Williams in Washington and special correspondent Jonathan Ingram in Atlanta contributed to this report. Goldstein reported from Washington, Pressley and Rosin from Atlanta.

Recent Workplace Shootings

1. Dec. 18, 1997: Arturo Reyes Torres, 43, walks into a maintenance yard in Orange, Calif., with an AK-47 and kills his former boss and three others. Torres, who blamed the supervisor for getting him fired, is later fatally shot by police.

2. March 6, 1998: Matthew Beck, 35, a Connecticut Lottery Corp. accountant involved in a pay dispute, fatally shoots three of his supervisors and the lottery president in Newington, Conn., before killing himself.

3. Jan. 14, 1999: De-Kieu Duy, 24, opens fire in a Salt Lake City office building, killing one person and wounding another.

4. March 18, 1999: Walter V. Shell, 71, turns himself in after allegedly shooting to death his attorney and one of his clients in Johnson City, Tenn. Shell blamed the lawyer for a $100,000 loss in a dispute over his ex-wife's will.

5. April 15, 1999: Sergei Babarin, 71, opens fire in the Mormon Family History Library in Salt Lake City, killing two people and wounding four others before police shoot him to death.

6. June 11, 1999: Joseph Brooks Jr., 27, fatally shoots his former psychiatrist and a woman at the doctor's Southfield, Mich., clinic. Four others are injured before Brooks kills himself.

Source: Associated Press