A soldier accused of plotting a terrorist attack near Fort Hood, Texas, appeared in court Monday wearing a face mask, the Austin American-Statesman reported. Pfc. Naser J. Abdo\'s trial began Monday with the selection of 13 jurors, including one alternate, the newspaper said. Abdo was arrested July 27 at a Killeen, Texas, hotel near Fort Hood with weapons, enough gunpowder to make at least one bomb and bomb-building instructions from an al-Qaida magazine. Abdo wore the face mask in court to protect the U.S. marshals guarding him. Officials said Abdo last month bit his cheek and spit blood at prison officials. Abdo wrote a letter to the Waco Tribune-Herald saying he deliberately infected himself with human immunodeficiency virus to \"punish the enemies of the faithful.\" He was tested for the virus that causes AIDS, but the results were not revealed. An observer of the case says prosecutors may have problems proving intent. Several attorneys said the allegations were an \"inchoate offense,\" one not carried out, and could be hard to prove. Prosecutors said they have a statement they say Abdo gave in which he discussed killing soldiers and their loved ones in a Killeen restaurant. \"The government is going to have to prove its case and the defense is going to be looking very closely at making the government show that he knowingly and intentionally engaged in this violence,\" Jeffrey Addicott, who heads St. Mary\'s University\'s Center for Terrorism Law, told the San Antonio Express-News. \"That\'s a little hard for the government because the act didn\'t take place.\" Abdo, 22, a Muslim infantryman claiming conscientious objector status, faces nine charges, including attempting to use a weapon of mass destruction and attempted murder. The Army said Abdo fled his post after being charged with possession of child pornography. During the last 10 months, Abdo has interrupted hearings with outbursts and claims of having tried to infect his guards with HIV by spitting blood at them, the American-Statesman said. From his cell, Abdo told a Tennessee television station he originally planned to kidnap an officer at Fort Campbell, Ky., then videotape his execution, the Austin newspaper said.