NEW YORK ( TheStreet) -- Jared Lee Loughner, the man accused of the mass shooting in Tucson, pleaded not guilty on Monday. The Jan. 8 shooting killed U.S. District Judge John Roll, a congressional aide, a 9-year-old girl and three others. Thirteen were injured, including Rep. Gabrielle Giffords, who was shot in the head. Loughner, 22, faces federal charges of trying to murder Giffords and two of her aides. He will face state charges regarding the other victims at a later date. The case against Loughner is being heard in Arizona by a judge from San Diego, Judge Larry Alan Burns, after the federal judges in Arizona declined to take the case. A number of investigators have said Loughner may have been mentally disturbed in the weeks leading up to the shooting. If his attorney successfully pleads not guilty using mental competency as a defense, Loughner could be sent to a mental health facility instead of being sentenced to prison or death. --Written by Theresa McCabe in Boston. >To contact the writer of this article, click here: Theresa McCabe. >To follow the writer on Twitter, go to @TheresaMcCabe. >To submit a news tip, send an email to: firstname.lastname@example.org.