If convicted, Sharif Mobley of New Jersey could face the death penalty.
The 26-year-old American of Somali descent was arrested on suspicion of having links to Al-Qaeda and attempted his escape in March while receiving treatment at a Yemeni hospital for a leg condition. Authorities say he fooled his hospital guards into unshackling him by asking to join them for prayers and then killed a guard who had laid down his weapon.
The official spoke about his trial on condition of anonymity because he was not authorized to speak to the media.
US officials say Mobley, who grew up in Buena, New Jersey, traveled to Yemen more than two years ago with the goal of joining a terror group and that the US government was aware of his potential extremist ties long before his arrest.
While living in the United States, Mobley passed a criminal background check and worked as a laborer at several nuclear power plants, but there is no indication that his work had any connection to his alleged involvement with terror groups.
Separately, a Yemeni counterterrorism official said Tuesday that authorities have since June deported 25 foreigners, including Americans, suspected of having links to Al-Qaeda.
The official, who also spoke on condition of anonymity, said all 25 confessed to having made contact with American-Yemeni radical cleric Anwar Al-Awlaki and Omar Farouk Abdulmutallab, the Nigerian suspect in the failed attempt to blow up a Detroit-bound airliner on Christmas Day.
The official did not say how many Americans were among those deported. The 25 included citizens of France, Britain and Asian nations, he said.
A number of foreigners remain in detention because of suspected links to Al-Qaeda, said the official. He did not elaborate.
In June, the US State Department said only three out of 12 Americans being held in Yemen have been detained on terror-related charges.
Yemen's weak central government has struggled with a growing Al-Qaeda threat from militants who are increasing their operations in the impoverished and largely lawless country on the southern tip of the Arabian Peninsula.
Al-Qaida's offshoot in Yemen amassed strength after key leaders escaped from a Yemeni jail in 2006. In 2009, it was further bolstered by a merger with Saudi Al-Qaeda militants to form Al-Qaeda in the Arabian Peninsula.
The US Embassy, which was attacked twice by Al-Qaeda in 2008, barred its personnel from nonessential travel outside Yemen's capital. Tuesday's decision was in response to "continuing threats from Al-Qaeda," an embassy statement said.
