dF sted in Firing Device Found .-In Home, Court Told By Jim McGee and Rachel Stassen-Berger Washington Post Staff Writers NEW YORK, March 25 Th Pe, bing of th investigation of the bom World Trade Center reached a new plateau Thursday withthe arreg of *-fifth sus ct and disc=Mof new Evidence against a circle of Middle Eastern immigrants from the New York-New Jersey area. Today's developments began shortly after midnight, when 'FBI agents in Newark placed IML 27 mnder arrest AQ" after sev- e era 0@,s ra ours f questioning. Later in the day he was formally charged with "aiding and abetting" the: bombing, which killed six persons, injured more than 1,000 and crip- pled one of the world's largest of- fice complexes. When FBI agents arrested Nidal A. Ayyad, a chemical engineer im- lip Esposito's counterpart in New York, FBI Assistant Director Jim Fox, cautioned that it, may be -,Wonths before the investigation is -complete in the case, which defense attorneys are quick to note is based-so far as is publicly under- stood-on evidence that is largely circumstantial. "The investigation is continuing on a large scale," Fox said at the news conference. Each of the five suspects now in custody appeared in federal court on separate charges related to the bombing, but a federal prosecutor of the de- said in court that plicated in the case, on March 10, he was carrying an American Ex- in the name of Alkaisi. press card American Express records listed % Ayyad's residence as the billing ad. dress for the card, the federal com- plaint'said. A search of Ayyad's residence the same day turned up a "timing mechanism which had been mod- ified .... as a time-delay firing sys- tem, consistent with timing mech- anism used in other terrorist bombs," according to the complaint. In related court proceedings to- day, Ayyad and three other sus- pects pleaded not guilty to charges -involving the Feb. 26 explosion in the trade center's underground parking garage. While they are optimistic after five arrests within a month after the senior officials said they are still unsure about the motive. "The circle is now very narrow in terms of the individuals we are still seeking who we believe are respon sible for thistombing," said Jim Es- posito, special agent In charge of -t Mottve VoHrAiPtomftinl Z clear,", some fendarits can expect to be re-in- dicted within a week under a more comprehensive set of charges Such a step, known as a superseding in- dictment, might define in greater detail the legal underpinnings of the, government's case. "I ... am ... not ... guilty," said Mohammed A. Salameh, his' loud VUD@@ aboWtliie din of the courtroom. Salameh, the first arrested in connection with the bombing, rented a van that the FBI alleges was used to carry the explo- sives. Moments later, 4.,M-d, who is implicated in the case a's @aresult of his dealings with Salameh, stood up and gave a prepared statement: "I swear by all I hold dear-the Koran, my wife, my children, my mother-I am not guilty," he said. "I had nothi g to. do with this." n Minutes later, Ibrahim A. El- g@ 42, was-Feif -H@to the s4me tourtroom, where . he was greeted with a bear hug from Wil. liam N. Kunstler, his defense attor- ney, known for his representation of, structing the search of his rosi- dence and possessing fraudulent passports, but the U.S. Attorney's office has publicly connected him with the bombing indictment. "Not guilty' said Elgabrowny. - According to the indictment un- sealed today, the grand jury 'charged Salameh, Ayyad and Ma- hmud Abouhalima, an Egyptian flown here from his homeland on Wednesday, with causing the bomb. ing of the trade center. Abouhalima "was beaten, he was Aortured," during 10 days of con@ finement in Egypt, his defense at torney, Jesse Berman, told the. ..court. In the hallway after the hear-': ing,, Berman told reporters thaf Abouhalima claimed that his inter-' ...rogators.in Egypt tortured himwit cigarette burns to his genitals an demanded that he confess to in-. volvement in the bombing. A spokesman -for Egypt's Interio Ministry said today he did not kno "anything about" the charges Washington Post corresponden Caryle Murphy reported from Ca' ro. "Telephone again after tomo row," he said. - Alkaisi was brought before magistrate, but did not enter a plea The federal complaint said that a least one witness saw Alkaisi wi Salameh before the bombing, at storage shed in New Jersey whe' agents discovered a cache of - che icals that can be used to create e'. Olosives; During questioning at the wark FBI office, - Alkaisi @'statedy .,pa e- substance and in rt that h notknow Salameh-well and onl,@, contact with him' through Elgabrowny is charged with ob- shed. Mahmud AWuhalima, center, an Egyptian, is arraigned in New York courtio-0ii on cOrTe-sof causing Feb. 26 bombing. of the World Trade Center.