More than a year after the body of a Fairfield University sophomore was ditched on a Brooklyn street, investigators yesterday finally tracked down the suspected gunman, charged with killing his victim for $20.

“People do strange things for money,” Brooklyn’s district attorney, Charles Hynes, said. “Twenty dollars doesn’t seem like a hell of a lot, but maybe that’s what set it off.”

Antonio Russo, 18, of Brooklyn, was arrested for fatally shooting Mark Fisher, 19, of Andover, N.J., on October 12, 2003, at an upscale Kensington neighborhood south of Prospect Park.

“The wall of silence surrounding the murder of Mark Fisher has finally been breached,” Police Commissioner Raymond Kelly said.

He said detectives were initially stymied by a lack of cooperation from potential witnesses, but that the police investigation led not only to the arrest of Mr. Russo, but also of John Guica, on charges connected to an unrelated shooting in Florida. Mr. Guica hosted the party near the street where Fisher was killed.

Mr. Russo, who was 17 at the time of the shooting, is to be arraigned today at Brooklyn criminal court for second-degree murder and first-degree robbery and could face 25 years to life if convicted, Mr. Hynes said.

Mr. Russo shot Fisher at 6:38 a.m. after the two left a party at Mr. Guica’s home at 152 Stratford Road, Mr. Kelly said. Mr. Russo allegedly killed Fisher while he sat in a car in front of 150 Argyle Rd., about a block and a half from the scene of the party, and then took the body from the car and dumped it in the street. According to Mr. Hynes, the body was “found lying on a blanket in the street in a pool of blood.”

Following the shooting, Mr. Kelly said Mr. Russo cut his braids and went to California, but could not find a permanent residence on the West Coast and then returned to New York. Mr. Russo, who had no criminal background, was arrested without incident at 11:35 a.m. yesterday in front of his residence at 60 Turner Place by detectives from the 70th Precinct at Kensington.

Nine people attended the party at the home of Mr. Guica, 22, but Mr. Hynes said investigators were stymied by “lawyered up” witnesses who refused to cooperate. Fisher’s parents, Michael and Nancy, offered a $100,000 reward for information about the killing, but the gesture failed to net anything useful and Mr. Hynes said no one is eligible to collect the reward.

According to police, Fisher was hanging out with friends from his Connecticut college early on October 12,2003,at the Bar Harbor club on the Upper East Side. Fisher took a liking to Meredith Denihan, a friend of classmate Angel Di Pietro. When some of the students were denied service because they lacked valid identification, Mr. Guica suggested they go to his home at 152 Stratford Road because his parents were staying in Florida. Fisher left the bulk of his college friends behind at 2 a.m., when he went to Brooklyn with Ms. Denihan, Ms. Di Pietro, and her boyfriend, Tommy Saleh, Mr. Guica and his half-brother, Matt Giuliano, Albert Cleary, and Gminski Arty.

At 4:30 a.m. they arrived at the house and were joined by Mr. Russo, police said. A half hour later, Fisher went to a nearby ATM with Mr. Russo and withdrew $20, and then returned to the house. At some point, Mr. Russo stole the money. At about 6:30 a.m., Fisher left the Guica home and then Mr. Russo shot him several times, police said.

Fisher’s body was soon discovered but he had no identification. His wallet with his driver’s license and ATM card was discovered days later in a nearby storm drain.

Mr. Guica has no convictions, but investigators said he was arrested twice since the shooting. Mr. Guica was arrested at a Florida nightclub on July 4 and charged with first-degree attempted assault for shooting at someone during a dispute, missing his intended victim. On September 30, Mr. Guica was arrested on a Brooklyn street corner for buying narcotics while wearing a bulletproof vest, and is currently free on bail.

“This case is not closed,” Mr. Kelly said, and there may be further arrests.