LOS ANGELES, DEC. 9 -- David Burke's worst days, until the puzzling and tragic events that led to his death in a California air crash Monday, came seven years ago when his younger brother Joseph died of a heroin overdose.

Burke had tried everything to straighten his brother out, his friends said. But he was away from home during Joey's last hours, and when he returned to find his brother had died in the bathroom in the half of the duplex he rented from his brother, Burke seemed to pull within himself as tight as a clenched fist.

Jo Ann Smith, the mother of three of Burke's seven children, said he blamed himself for his brother's death but could find no release for his pent-up feelings for weeks, until he finally erupted in a fit of sobs.

As FBI and National Transportation Safety Board investigators move closer to blaming the deaths of the 43 persons who died in Monday's crash on a sudden fit of rage by Burke, the friends and relatives of the 35-year-old USAir ticket agent are trying to sort it out. Interviews with those in his home town of Rochester, N.Y., portray a bright, ambitious man who cared for his children -- he had seven by five women -- and who fumed at what he felt was the racial discrimination that kept him from promotions in the airline industry he loved.

The David Burke they describe -- husky but handsome, sometimes mistaken for the television actor Demond Wilson -- also succumbed to dark moods that led him to shout at his children and girlfriends. He seemed particularly concerned about money. From the time he worked as a delivery boy in high school he saved every dollar he could, later spending them on houses, cars, including a gold Mercedes, fine clothes, expensive cognac and, always, women.

Burke remained close friends with Smith, visiting her often and sharing the cost of raising their children even after they ended their 14-year relationship in 1984. She said he described his dismissal from USAir last month as only a suspension and said a company hearing was scheduled to lift the suspension.

Last week, she said, he called to say he wanted their three daughters to come see him during the holidays. "He told me," she said, " 'I've got something to do Monday, but I'll call you back after that and tell you which flight to put them on.' That was the last I ever heard from him."

Burke, who worked at Los Angeles International Airport, was arrested Nov. 15, and fired Nov. 19, for the alleged theft of $69 of the proceeds from in-flight liquor sales. The criminal charge was later dropped for lack of evidence -- despite a videotape of the alleged theft -- and until the last day of his life Burke seemed determined to get his job back. Smith said both she and Burke were investigated, but never charged, for similar thefts at the Greater Rochester International Airport, where he worked for 13 years. Rochester police say they also investigated him for narcotics sales and automobile theft, but never charged him.

At work, his USAir colleagues say, he was competent, conscientious and eager to please. An earlier effort to take legal action against USAir for discrimination hurt him, he thought. But he was given a supervisory job three years ago, and still seemed intent on becoming a station manager -- the boss of one of USAir's airport customer service operations. Friends said he was crushed when he had to accept a demotion to the job of ticket agent after he transferred to Los Angeles to be near another USAir agent he hoped to marry. And he was disappointed that a white woman with only four years' experience was made a supervisor.

David Augustus Burke was born May 18, 1952, in London, the son of Jamaican immigrants. The family soon moved to Rochester, where Burke's father, Altamont Burke, became a successful taxicab driver. Altamont Burke developed many friendships at the Rochester airport where his son would later work. David Burke's parents had four sons including Alan, Joseph and Altamont Jr., and a daughter, Valerie.

At Madison High School, David Burke was a chubby, quiet boy who earned As and Bs, but spent much of his time working on his green Dodge Roadrunner. He dated Smith there, and by the time he was a senior and she a junior, they had their first daughter, Lisa. "His father was really upset, but {David} stuck with us," said Smith, who raised the infant in her grandmother's house. "If he had $20, he would give me 10 to help with the baby."

At his father's urging, Burke spent a year at the State University of New York at Binghamton, but told Smith "college wasn't for him" and enrolled at a school that trained airline customer service agents.

He worked in a tool-and-die factory for a year before getting a job with USAir in Rochester in 1972, where he worked as a baggage handler for four years before winning promotion to an agent job inside the terminal.

After his first year with USAir, he and Smith pooled their resources and bought a $28,000 duplex in the mostly white portion of Rochester called the 19th Ward. In the late 1970s, Burke accepted a better-paying job at National Airport in Washington and lived with a high school friend attending Howard University. But he often returned to Rochester on weekends and after a year arranged a transfer home.

The FBI has information that Burke allegedly took a .44-caliber Magnum on PSA Flight 1771, with an intention to kill his former USAir supervisor, Raymond F. Thomson, and bring down the aircraft. But Smith said Burke did not serve in the military and never owned a gun while she knew him. She said he kept a baseball bat or crowbar at the house for protection and encouraged his father, who owned a gun, to get rid of it.

Smith said she and Burke discussed marriage, but she insisted his affairs would have to stop if they wed and he indicated he did not want to do that. A year ago he told her that he was finally serious about marrying another USAir ticket agent, Jacqueline Holt, whom he had known for several years.

Smith said he told her, " 'I'm ready to settle down.' "

When Burke's daughter Sabrina encountered trouble at home, he brought her to live in his new three-bedroom, two-story townhouse in Long Beach, 25 miles south of here. Holt, who also uses the name Camacho, lived in Hawthorne near the airport where she also worked and was often at the townhouse, neighbors said.

The Associated Press reported she obtained a temporary restraining order in October barring Burke from contact with her after he allegedly tried to choke her, disabled her car and damaged some of her clothing.

One government source said that Burke left a message for Holt on his answering machine saying he was sorry, but he planned to bring down both Thomson and "the world."

Smith said Burke was extremely budget-conscious, asking the price of each dress she bought and prompting her to claim some new dresses were actually old ones so he would not make her take them back. But he was usually generous with his time and thoughtful to his children.

To rehabilitate his brother Joseph, who had served two years in prison for arson, Burke arranged a job as a skycap and rented him the other half of the duplex. After Joseph died, Burke berated himself for not being there the evening he took his last dose of heroin.

Smith said the police investigated whether Burke was involved in drug-dealing because he was friends with several Jamaican immigrants who were arrested in a large drug bust. The Rochester Times-Union said one of Burke's friends, whom they did not identify, said the ticket agent was a cocaine dealer "using his airport connections" to move a large quantity of narcotics. Rochester police said he was never charged.

The charge that he stole $69 "doesn't make any sense," Smith said. "He had money. He sold two houses before he left Rochester." She said he seemed confident he would get his job back. USAir does allow fired employes to appeal the decision. A company spokesman would not comment on what action Burke might have taken. A spokesman for a Los Angeles city attorney said that a USAir official before the crash had asked to see a city attorney Tuesday about the decision to drop the charge against Burke.

Smith said Burke was often reluctant to discuss what was bothering. She said she does not believe he could have caused Monday's crash, but if he did, the exact reason is probably something "we will never know."