A second young Jamaican immigrant, Nathaniel O. Osbourne, emerged a potentially important figure in the sniper investigation yesterday when he was arrested in Flint, Mich., as a material witness.

Osbourne, 26, is listed on registration papers as a co-owner of the car allegedly used in the shootings, along with John Allen Muhammad, who has been charged in a warrant with murder.

FBI officials said they know of nothing to suggest that Osbourne knowingly assisted Muhammad as a part of any conspiracy. "At this point in time we're considering him nothing more than a material witness," an FBI spokesman said last night.

Federal law permits prosecutors to seek the arrests of people who are believed to have valuable information about criminal cases. They must first show a judge that the possible witness poses serious risk of fleeing or failing to appear.

Osbourne was described yesterday as a slightly built restaurant worker and aspiring singer who had lived at addresses in New Jersey.

After he did not respond to televised pleas, the FBI and New Jersey police began a search of his former haunts in Camden and Trenton and eventually were led to a home on Flint's low-income north side.

He was arrested by FBI agents and local police without incident around 9 a.m., officials said.

Federal sources said yesterday that Osbourne was "fully cooperating." He is expected to make an initial appearance in federal court in Flint this morning.

A relative in Camden, Evelyn Graffie, said yesterday that she had no knowledge of any possible involvement of Osbourne in the sniper case or how he turned up in Flint.

"I'm dying to catch this boy and find out what's going on," she said.

Graffie said Osbourne came to the United States a few years ago, first bunking in a crowded Bronx apartment with his mother and grandmother, then moving to Graffie's block in Trenton.

He was always singing, she said.

"In the bathroom, he's singing. When he's eating, he's singing," she said. "He just tries to make songs and sing."

Rozz White, a former New Jersey neighbor of Osbourne's, said that when she knew him he was attending community college and working for a restaurant and pool-service company.

This year, Osbourne went to work at All Nations Cuisine, a small Caribbean restaurant in Camden. The owner, a distant relative named Michael Clarke, allowed him to live in an office above the restaurant for about five months.

The restaurant's address appeared on registration papers filed Sept. 11 with the New Jersey Division of Motor Vehicles for the 1990 Chevrolet Caprice that officials believe was used in the shootings.

Clarke said Muhammad came to the restaurant about three times in August. Their conversations never went beyond small talk, and he never saw the Chevrolet Caprice. "I think John just befriended [Osbourne] and asked him to do a favor," Clarke said.

Osbourne has apparently been in Flint since before Muhammad was arrested. The Rev. Charlie F. Byrd, pastor of a church in Flint, said a woman who belonged to his congregation brought Osbourne there Wednesday for possible premarital counseling. Byrd said he was told that the two met at a school for truck drivers.

Kunkle reported from New Jersey and Argetsinger from Washington. Staff writers Colleen Jenkins and Martin Weil contributed to this report.

NATHANIEL OSBOURNE

FBI agents escort Nathaniel Osbourne, second from right, to a car to be transported to the Genesee County jail in Flint, Mich. He is being held as a material witness in the case. Federal sources said he was "fully cooperating."