The weekend of Labor Day 1993, the bodies of 36-year-old Debra Barton and her mother, Eloise Spivey, were found in a blood-spattered camper on the edge of an Alabama lake.

The local sheriff has never found the sharp, heavy blade used to murder the two women while they were on a weekend fishing trip away from their homes in Lithia Springs, Ga. There has never been an arrest. But law enforcement officials and the women's relatives have long considered Mark Orrin Barton the "one and only suspect" in the deaths of his wife and mother-in-law.

"The motive here was a lot of anger: kill, kill, kill," Jerry Wynn, a sheriff's investigator, said a few months after the slayings.

Yesterday, there was a horrible sense of deja vu when Barton, 44, was found dead in his dark green Ford Aerostar van after shooting more than a dozen Atlanta office workers and -- apparently -- killing his two children and second wife.

"I thought, `Oh no, not again.' That's the first thing in my mind," said David Lang, who used to be married to Barton's second wife, Leigh Ann.

Reached early last evening in Sumter, S.C., where he grew up, Barton's mother said she had not been watching the news and had not heard that her son was -- at the time -- being sought in connection with the office massacre. "A detective did call me and told me Mark was threatening," Gladys Barton said.

She would not discuss her son's life in detail, but said, "He worked the stock market a lot and lost some money." Asked about any prior trouble her son had encountered with the law, his mother replied, "I'd rather not say anything about that."

According to public records, Barton and his first wife, Debra, married in 1979. They had two children, Matthew, about 10, and Michelle, about 8. Both children and their stepmother, Leigh Ann Barton, were found yesterday, slain with a blunt weapon, at an apartment in Stockbridge, Ga., southeast of Atlanta, where the family had moved a month ago.

According to Henry County police, the two children were found on their beds, a handwritten note next to each of their bodies. Leigh Ann Barton's body was found in a closet with a note, as well.

A fourth note, this one typed on a computer, was left in the living room to explain "why he did what he did," according to Jimmy Mercer, the county police chief. The notes suggested that the wife may have been killed Tuesday and the children Wednesday.

Records show that Barton married his second wife in October 1995, slightly more than a year after his first wife's death.

Last night, Lang said in a telephone interview from Macon, Ga., that Leigh Ann and Barton had met while working together at a local chemical company -- he as a salesman, she as a receptionist and shipping clerk. They became romantically involved while both were married to their first spouses, Lang said he learned after the fact.

Less than a month after Barton's first wife and her mother were murdered in their camper, Lang said, "I came home from work one day, and my house was empty. She had moved out. He was the cause of it."

A few days later, Lang said, "I got a phone call late one night from the sheriff's department . . . asking if I knew [Barton] and wanting to verify the whereabouts of my wife on certain nights." Because Lang worked a night shift as a machine operator at a Boeing Co. plant at the time, he told the investigator he could not. He said he never met Barton.

In that conversation and two subsequent phone calls from investigators, Lang said he learned that Barton had taken out a large life insurance policy on his first wife a few weeks before her death, and that his own wife, Leigh Ann -- to whom he had been married 1 1/2 years -- had taken out a $250,000 insurance policy on him. He said investigators told him they believed Leigh Ann's car had been in Barton's driveway the night of the murders.

According to neighbors in Morrow, Ga., where Barton, his children and his second wife lived for about two years, Barton's second wife moved out in June. But the couple appeared to reconcile quickly, because Barton and his two children gave up their rented house in Morrow to move into his wife's new apartment.

It was at that apartment where police found their bodies yesterday. Apparently, they were killed before Barton turned his sights on the stock trading firms.

Last evening, many of the family's former neighbors on Sinclair Place in Morrow gathered in the middle of the usually peaceful street, some talking on cellular telephones as they fielded calls from journalists around the country.

Rebecca Earls has lived for 23 years in what she called a "typical, middle-class" street on which a blend of newcomers and longtime residents live. It was the kind of place, she said, in which "if you've got a problem, the whole neighborhood rallies round." But Barton, she said, was conspicuously less neighborly. "If you saw him on the street, if you waved, sometimes he'd acknowledge you and sometimes he'd act like he didn't see you. . . . The kids were pretty much parked at the neighbors, and dad was on the computer all the time."

Another neighbor, Cindy Northcutt, said Barton's children often spent hours at her house, especially when her young nephew was visiting. "The little girl was absolutely gorgeous and sweet," often carrying her pet cat draped on her shoulder.

Northcutt said Matthew had seemed more withdrawn, often immersed in Nintendo games. She said that Barton's wife, Leigh Ann, was from Athens, Ga. "She was nice," Northcutt said.

At the Stockbridge apartment complex, 16-year-old Justin Randall said he ran into Barton and his son Tuesday evening. Both were wearing Boy Scout uniforms and were on their way home from a scout meeting at a church in Morrow. "He seemed very normal," Randall said.

Records show that Barton had an investment interest in a company called Microblend, which is based in Daphne, Ala., but also has an address in Stockbridge.

Yesterday, Harvey Houtkin, the president of All-Tech Investment Group, said from the company's headquarters in Montvale, N.J., that Barton had been a day trader with the firm for about a year until April.

Last night, Lang said, the fresh deaths, coming six years after the first pair of slayings, seemed senseless. "If something could have have been done earlier to put this man behind bars, then none of this would have happened."

Special correspondent Jonathan Ingram in Atlanta contributed to this report.