The plea by Jared Lee Loughner marked his second court appearance since he allegedly shot the congresswoman and 18 others Jan. 8 at Giffords' meet-and-greet event outside a grocery store in Tucson. Six people, including U.S. District Judge John Roll and a 9-year-old girl, died. Thirteen others were wounded.
Loughner, 22, faces federal charges of trying to assassinate Giffords and attempting to murder two of her aides. Later, he will face state charges dealing with other victims.
At least eight U.S. marshals were present at the hearing in the Phoenix courthouse, where Loughner entered in the afternoon smiling and wearing an orange prison suit and glasses. His hair, shaved in the mug shot that's become an enduring image of the tragedy, has grown out slightly.
Investigators have said Loughner was mentally disturbed and acting increasingly erratic in the weeks leading up to the shooting. If his attorney uses mental competency questions as a defense and is successful, Loughner could be sent to a mental health facility instead of being sentenced to prison or death.
U.S. District Judge Larry Burns of San Diego asked Loughner attorney Judy Clarke whether there was any question about her client's ability to understand the case against him.
"We are not raising any issues at this time," Clarke said.
Giffords was shot in the forehead and spent two weeks in a Tucson hospital before she was flown Friday to Memorial Hermann Texas Medical Center Hospital in Houston. Shortly after her arrival, doctors said she had been given a tube to drain a buildup of brain fluid that has kept the Arizona congresswoman in intensive care.
The hospital gave no update yesterday.
A hospital statement said Giffords would continue to receive therapy "until her physicians determine she is ready for transfer" to a nearby center where she would begin a full rehabilitation program.
Prosecutor Wallace Klein-dienst estimated that he would know within the next 30 days whether additional federal charges would be filed against Loughner. Kleindienst said prosecutors provided defense lawyers with records taken from Loughner's computer and documents of about 250 interviews made in the case.