BUENOS AIRES, May 1 (JTA) — A key witness in the trial of 20 people accused of helping to bomb Buenos Aires´ main Jewish community center has refused to answer a crucial question. Used-car dealer Carlos Alberto Telleldin, an expert in selling and assembling stolen car parts, is accused of supplying a van to former police officers. The officers allegedly loaded the van with some 600 pounds of explosives used in the 1994 attack, which killed 85 people and wounded 300. Testifying Monday, Telleldin spoke at length about his skills as a thief — but refused to say to whom he gave the van used in the attack. "I am not going to talk about that," he told the packed courthouse. Telleldin, who has been studying law while in jail, denounced alleged pressure from former President Carlos Menem and investigative judge Juan Jose Galeano, who Telleldin claimed tried to influence his testimony. Telleldin said he had considered the sale of the van just a routine business deal. "I never thought the van was going to be used for a terrorist attack," he said. Prosecutors had anxiously awaited Telleldin´s testimony to see if he would finger the former police officers, and their disappointment was evident. "Telleldin´s attitude of not speaking about the most important issue shows his complicity with" one of the former police officers under suspicion, prosecutor Alberto Nisman said.