The army psychiatrist is on trial for killing 13 people and wounding dozens more in a 2009 shooting spree at Fort Hood.
Prosecutors charged Hasan with 13 counts of premeditated murder and 32 counts of attempted premeditated murder.
Hasan, who has said the United States is at war with Islam, is representing himself at his military trial, in which he faces a possible death sentence if he loses his case.
Hasan never denied he was the killer and claimed he was defending the Taliban leadership, the (Austin) American-Statesman reported.
Because he is representing himself, Hasan, who has twice fired court-appointed attorneys, can cross-examine his victims and testify, but he declined Tuesday to cross-examine Sgt. Alonzo M. Lunsford, who testified Hasan walked in front of him, twice shouted "Allahu akbar" ("God is great" in Arabic) and opened fire.
Lunsford, who was unarmed, was shot in the head and body. He said he played dead, but when he tried to exit the building, Hasan followed him and shot him in the back.
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