Mohamed Rashed Daoud Al-'Owhali, 24, had argued in court papers that his confession was coerced by U.S. investigators who threatened to hang him "like a dog" unless he cooperated. Prosecutors denied he was coerced.
U.S. District Judge Leonard Sand initially barred the statement but changed his mind after prosecutors said Al-'Owhali had been informed of his right to a lawyer.
Sand concluded that Al-'Owhali's decision to waive his right to a lawyer and speak to investigators "was a consequence of the strong desire he expressed to be tried in America so that he could confront directly his avowed enemy."
Sand, speaking from the bench Monday, informed lawyers of his decision and promised a written ruling would be issued later addressing the "significant, novel and complex legal and factual issues" in the case.
Al-'Owhali was arrested five days after the Aug. 7, 1998, bombings in Nairobi, Kenya, and Dar es Salaam, Tanzania. The attacks killed 224 people, including 12 Americans.
The trial for Al-'Owhali and three other alleged followers of terrorist mastermind Osama bin Laden began Jan. 3. Opening statements are expected to begin as early as next Monday.
Prosecutors have charged 22 men in the bombings, and Al-'Owhali and another defendant could be sentenced to death if they are convicted. Bin Laden and 12 others remain at large.
Al-'Owhali, a Saudi Arabian, is accused of tossing a stun grenade at a guard outside the embassy in Nairobi and throwing away keys to the bomb-carrying vehicle and bullets to a gun found in it.
Prosecutors said he confessed the bombing was meant as a suicide attack.
The defendants have all maintained their innocence, challenging the government's right to stage the trial in the United States and to use evidence gathered in foreign lands by methods they say would be illegal under U.S. standards.
America was targeted because its way of life clashed with the group's extremist interpretation of Islam and because it supported other governments and institutions including Saudi Arabia, Egypt, Israel and the United Nations, prosecutors said.
In all, prosecutors have charged 22 men. Five are awaiting trial in New York, three are awaiting extradition from Britain and 13 remain at large. The other man has confessed, and that confession was ruled admissible.
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