The suspect in the shooting of Democratic Congresswoman Gabrielle Giffords pleaded not guilty in court, the 22-year-old's first response to the charges.
Two weeks after the deadly attack outside an Arizona grocery store, Jared Loughner's grinning mug shot has become an enduring image of the tragedy.
Loughner did not speak but smiled in court and wore an orange prison jumpsuit and glasses, and his wrists were cuffed to a chain around his waist as eight US marshalls kept watch in the packed Phoenix courtroom.
Loughner faces federal charges of trying to assassinate Ms Giffords and kill two of her aides. More charges are expected later.
Investigators have said Loughner was mentally disturbed and acting in an increasingly erratic manner in the weeks leading up to the attack on January 8 that wounded 13 and killed six.
If Loughner's lawyer uses mental competency questions as a defence and is successful, Loughner could be sent to a mental health facility instead of being sentenced to prison or death.
Ms Giffords was shot in the forehead and spent two weeks in a Tucson hospital before she was flown to Memorial Hermann Texas Medical Centre Hospital last Friday.
The judge set a March 9 hearing to consider motions.