An FBI agent testifying in the trial of the suspected Bali bomb-maker said on Thursday that the accused had been identified as an explosives expert by other Islamic militants and had planned to kill US troops.
Indonesian prosecutors accuse Umar Patek, who was arrested last year in the same Pakistani town where US commandos later killed al-Qaeda chief Osama bin Laden, of constructing the bombs that killed 202 people, mostly Westerners.
Frank Pellegrino, a special agent with the Federal Bureau of Investigation who interrogated many Islamic militants following the 9/11 attacks in the United States, arrived in Bali shortly after the October 2002 nightclub bombings on the holiday island.
Pellegrino said he interrogated around 20 Islamic militants, most from the al-Qaeda linked Southeast Asian terror network Jemaah Islamiyah (JI), of which Patek is believed to be a key member and which was behind the Bali attacks.
"Many did know Mr Patek and all described him -- especially after the time of Bali bombings -- as a leader, a bomb-maker, a well-known bomb-maker who knew how to mix chemicals and knew how to teach people how to mix chemicals," Pellegrino testified at the trial at the West Jakarta District Court.
Pellegrino was one of the FBI agents responsible for tracking self-confessed 9/11 mastermind Khalid Sheikh Mohammed, who was caught by Pakistani authorities on March 1, 2003.
He said the FBI had already been looking into JI because of threats of an attack on the US embassy in Singapore in 2001.
Patek's name was quickly known by the FBI after the Bali attacks, Pellegrino said.
"A very famous sketch was drawn of what he looked like," he told the court. "We realised pretty quickly it was Jemaah Islamiyah," he added.
Pellegrino said he had many discussions with Indonesian police following the Bali attacks about Patek's activities in Afghanistan, where the suspected bomb-maker is known to have trained.
"He continued being a terrorist, he continued making bombs and was planning to attack US troops in the Philippines," he testified.
Patek, 45, went on trial in February, charged with murder, bomb-making and illegal firearms possession. Prosecutors say they will push for the death penalty.
Three JI members -- ringleader Imam Samudra and the brothers Mukhlas and Amrozi -- were executed by firing squad in November 2008 for their roles in the Bali bombings.
According to the indictment, Patek was involved in assembling the bombs for the attacks and also strikes on churches in Jakarta on Christmas Eve 2000.
Two bombs exploded in Bali's Kuta tourist strip on October 12, 2002, one at Paddy's Irish Bar and the second shortly after in a van outside the nearby Sari club.