By JOHN KIFNER 

The man in the Clark Street subway station in Brooklyn was hurting.

His sneakers and the legs of his blue jeans were singed and shredded, his legs bloody below the knees, Police Officer Michael Ruiz remembered later. There were burns on his arm, some of the skin on his face was peeling away, and through the tatters of his gloves there were burn marks on his knuckles.

The two encountered each other about 10 minutes after 2 P.M. yesterday -- about a half-hour after a burst of flame in a crowded No. 4 train injured 41 people as the subway pulled into the Fulton Street station in the Manhattan financial district. Officer Ruiz and his partner in the 84th Precinct, Officer Anthony Roa, were answering a radio call for aid at the subway station in Brooklyn.

"I'm in pain," the man said, staggering near the token booth. They put him in an ambulance, although Officer Ruiz recalled that "it seemed a little odd how he got all the way into Brooklyn."

Then, as they sped toward the burn unit of New York Hospital Cornell Medical Center, a description came over their radios of a suspect in the subway  firebombing. They looked at the man riding with them: a white man, around 200 pounds, between 40 and 50, burgundy sweater, dark blue three-quarter-length coat, blue jeans torn below the knees, burn marks.

The two officers looked at each other. "Wait a minute," Officer Ruiz said. "That sounds like the guy that we have."

Less than an hour after the explosion, the police said, the man, identified as Edward Leary, 49, an unemployed computer technician from Scotch Plains, N.J., was the target of the investigation not only of yesterday's explosion but also of a similar incident last week. In that first incident, a teen-age girl's backpack suddenly caught fire on a subway train in Harlem, injuring and badly burning a 13-year-old boy, whose clothes had caught fire.

The main link between the two cases, the police said, were similarities in the construction of the incendiary devices that started both subway fires: each consisted of a glass jar about the size of a mayonnaise jar, filled with gasoline or another flammable liquid. Both had two wires leading from the liquid to a battery and a crude timer.

The police's Chief of Department, John Timoney, said the remains of the firebomb were being scrutinized by the police bomb squad and would be examined by the Federal Bureau of Alcohol, Tobacco and Firearms, which already has the remains of the first device. After questioning the two teen-agers burned in the Harlem case, the police said they concluded that the two had nothing to do with the device.

Mr. Leary, who was believed to have last worked for Merrill Lynch, lived at 63 Glenside Avenue in Scotch Plains and had co-op apartments at 10 Plaza Street in Brooklyn, a solid-looking brick building with a doorman facing Grand Army Plaza and Prospect Park.

"We did have an Edward Leary who worked for us," said Bobbie Collins, a Merrill Lynch spokeswoman. "We don't know if it was the same person. He worked in our operations department. He was terminated." Ms. Collins said the man last worked there in January 1994.

At the two-story white frame house in Scotch Plains, decorated with strings of blinking white Christmas lights, a neighbor said Mr. Leary had moved there from Brooklyn about a year ago, with his wife, Marge, a nurse-practitioner, and their son, around 12 years old. The neighbor, who would not give her name, said it appeared that Mr. Leary had been unemployed for the last few months.

Detectives who were parked in the driveway had seen gasoline canisters in the garage and a search warrant was being sought last night, said a law-enforcement official who asked for anonymity.

At the co-op building where Mr. Leary had lived in Park Slope, Brooklyn, he had left more distinct impressions. He was once president of the co-op board, a period recalled by one resident as one of "incredibly nasty politics" over running the building.

"Ed was weird," said David Elrich, who served on the board with him and who now lives elsewhere. "He was always involved in computers. He's your classic computer person, great with machines, not so good with people."

At one point, Mr. Elrich recalled, the infighting over the question of spending money to decorate the co-op building grew very emotional. One day, a mysterious fire erupted outside the apartment of the leader of the pro-spending faction, who opposed Mr. Leary's efforts to keep down maintenance costs. Law-enforcement officials said that after hearing tenants recall that incident last night, they were investigating whether Mr. Leary might be connected to it.

After he moved to New Jersey, Mr. Leary still kept the three apartments he owned in the Brooklyn co-op, Mr. Elrich said. One woman who rented one of the co-ops, Jeannette Goldstein, said she was involved in a long-running dispute over repairs she said were needed to the apartment, and produced a sheaf of documents and letters that she had sent to city officials.

"This man is driving me crazy," she said. "I'm on the phone all day long. He would not fix the apartment."

Mr. Leary had advertised one of the apartments in The New York Times on Sunday for $164,000. Last night, no one answered the family's New Jersey's phone number, which was listed in the ad.

Copyright 1994 The New York Times Company