In 1993, Barton was the prime suspect, although never officially charged with the murder of his first wife and mother-in-law.

Debra Spivey Barton, 36, and her mother, Eloise, 59, both of Lithia Springs, Georgia, were found in their camper van on 5 September 1993.

They were spending the Labour Day weekend at a lake in north-east Alabama.

The two women were found hacked to death with a sharp, heavy blade at the Riverside Campground in northeast Alabama.

The camper in which they were staying showed no signs of a forced entry, leading detectives to the conclusion that the murderer was known to the pair.

"He was the Number 1 suspect all the way through and still is," said Richard Igou, district attorney at the time of the killings.

Barton's father-in-law, Bill Spivey, said at the time: "Until the murders, Mark was the perfect son-in-law," adding, "since then, we have cooled tremendously toward each other."

Change of career

Some six years later and Barton had given up his career as a chemist and worked as a day trader - the practice of buying and selling shares with a quick turnaround, gambling on the movements of the stock market.

Barton lived a modest lifestyle in his Atlanta suburb home

Some of his trading was done through the All-Tech Investment Group's offices in Atlanta's northern Buckhead financial district.

There has been speculation that Barton's killing spree, which claimed the lives of nine people in Buckhead, may have been a sudden response to trading losses brought about by massive stock market fall on Thursday.

But Atlanta Mayor Bill Campbell said he thought the ups and downs of Wall Street were not to blame.

"Remember, there is at least some indication that there were fatalities ... that occurred before today," he said.

"So I think this clearly is a deranged individual."

Quiet churchgoer

Barton had lived in nearby Morrow for about a year, renting a two-story house in the modestly priced residential area.

Neighbours knew him as a quiet, churchgoing man, always working at his computer. Some described him as "preoccupied", others as "odd", a man who kept to himself.

He had married again but split with up with Lee Ann Barton earlier this year. Barton's two children, Michelle, 7, and Matthew, 12, moved with their stepmother to Stockbridge but Mrs Barton remained active in the local Scouts and was expected in Morrow on for an outing on Wednesday.