Authorities Find New Clues in N.Y. Explosion : Probe: Associate of key suspect may be linked to bomb-making gear discovered in N.J. apartment.

Authorities investigating the World Trade Center explosion have found bomb-making paraphernalia in a vacant New Jersey apartment believed to have been occupied by an associate of Mohammed A. Salameh, the prime suspect, sources said Saturday.

In addition, these sources said, hundreds of pounds of chemicals discovered Friday by the FBI in a public storage locker in New Jersey proved to be “very unstable” when samples were detonated by bomb experts.

“Can you imagine anyone driving around New York with that stuff in a van?” asked an investigator who declined to be identified.

If these chemicals prove to be identical to the materials used in the Feb. 26 trade center blast, it could support a theory held by some investigators that a bomb may have gone off prematurely in the parking garage underneath the massive twin-tower complex in Manhattan.

Salameh, a 25-year-old Muslim, has acknowledged that he rented the truck believed to have been used to transport the explosives into the trade center. In addition, investigators said they have identified him as the same man who rented the storage locker where the chemicals were found.

On Saturday, investigators were searching for a man described as a “Jordanian associate” of Salameh who accompanied him to a Ryder Truck Rental office in New Jersey on Feb. 23, when the truck was rented after $400 in cash was deposited.

They said this unnamed suspect apparently lived in an apartment at 40 Pamrapo Ave. in Jersey City, N.J., where FBI agents found the bomb-making paraphernalia. A neighbor told The Times that the occupants of the apartment, who kept odd hours, moved out shortly after the explosion.

By any standard, the investigation of the bombing has been unusually productive in its early stages, with the arrest of two suspects Thursday, the discovery of two separate caches of bomb-making materials Friday and an apparent link to a radical Islamic group.

Yet while federal officials are known to be optimistic about the inquiry, investigators admitted Saturday that they are a long way from being able to organize these puzzle pieces into a conclusive criminal case. They still have not resolved the basic question: Was it a well-planned act of international terrorism or simply the handiwork of a few fanatics?

Officials acknowledged that they have not yet established how many people may have been involved, whether the explosive materials unearthed so far are identical to those used in the blast and what grievances may have motivated the bombers.

The biggest clues may yet lie at the bottom of the 130-foot-wide, five-story-high crater in the bowels of the trade center, where investigators will search for evidence of the detonator, chemicals and other compounds used in the bomb.

Investigators worked over the weekend to stabilize the crater to allow further digging. But Raymond Finnegan, construction chief for the New York-New Jersey Port Authority, said: “It could take a week before we can get down there.”

Remarkably, the quick arrest of Salameh, who was living illegally in the United States, has not yet yielded the flood of information that might be expected from such an important early breakthrough.

Not only is Salameh refusing to cooperate with authorities, but he is not a well-known figure in his community. Even the landlord in the building where he has lived for several years has no recollection of him.

A second person arrested, Ibrahim A. Elgabrowny, who is also a Muslim, was taken into custody Thursday for obstructing the investigation, but officials have as yet found no evidence to tie him directly to the bombing.

Some parts of the case remain inconclusive and open to interpretation.

While Salameh is known to be related to a radical Islamic sect headquartered in Jersey City and he acknowledges renting the truck involved in the blast, Robert Precht, a public defender who is representing him, said authorities have yet to disprove his story that the truck was stolen from him before the blast.

“There is nothing in the complaint to contradict Mr. Salameh,” he said.

Likewise, Michael W. Warren, attorney for Elgabrowny, argued that the “real bombers” have eluded authorities.

Salameh’s defenders maintain that he established his innocence by returning to the Ryder rental office repeatedly after the blast, seeking reimbursement of his deposit. “It boggles the mind that a guilty party would do such a thing,” Warren said.

In addition, while the explosive ingredients found by federal agents in the northern New Jersey public storage locker are commonly available to any purchaser, anti-terrorist experts said these could be the tools of skilled professionals.

“The sophistication is in their simplicity,” one expert said.

The storage locker contained hundreds of pounds of nitric acid, sulfuric acid and urea, according to sources. While these chemicals have industrial uses, they are ingredients of nitroglycerin and have been used in the past by terrorists.

Sources said that when the chemicals were examined by federal bomb experts, they were found to be highly unstable. When the samples were detonated, the blast was described by authorities as “astounding.” Some investigators have speculated that the driver of the van could have been blown up in the blast if it was premature.

Jack Killorin, chief spokesman for the Bureau of Alcohol, Tobacco and Firearms in Washington, said investigators hope to find unexploded materials, bits of cloth, wire or tape in the crater to help them determine whether the materials seized match those used in the bomb set off under the trade center.

Salameh, who was born in the village of Biddiya in the Israeli-occupied West Bank and entered the United States in 1987 with a Jordanian passport and a one-year visa, is affiliated with the Al Salaam Mosque in Jersey City.

Members of the mosque have figured in the 1990 slaying of Meir Kahane, a right-wing Jewish leader, and a 1985 case involving the shipment of plastic explosives, blasting caps and a pistol silencer to Israeli-occupied territories.

The mosque is headed by Sheik Omar Abdul Rahman, who was tried and acquitted three times in Egypt on charges related to the slaying of Egyptian President Anwar Sadat. He has not been seen in New Jersey since the explosion.

M. T. Mehdi, spokesman for the blind sheik and secretary general of the National Council on Islamic Affairs, told The Times that he doubts the blast was the result of international terrorism. Instead, he theorized that the bombers were Palestinians frustrated with U.S. foreign policy.

“They are just nobodies, in the margin, but they are frustrated like all Arabs and Muslims are frustrated with the status of American foreign policy . . . and one day they go berserk,” said Mehdi, an American citizen. “The important thing is to try to understand what makes a young man like Salameh do such a beastly act.”

A Jordanian government statement issued Saturday confirming Salameh’s Jordanian citizenship expressed sadness about the link.

“We have received with deep concern the news that Mohammed Salameh, the prime suspect in the heinous, criminal and terrorist outrage of detonating an explosive device in the World Trade Center in New York, is a Jordanian,” the government said.

At the trade center, two construction crews working consecutive 10-hour shifts have succeeded in shoring up the garage with 22 steel braces, each of them 35 feet long. But officials still were cautious about entering the crater.

Times staff writers John Goldman, Robert L. Jackson, Elizabeth Shogren, Gebe Martinez and William Rempel contributed to this story.