A federal grand jury has indicted Jared Lee Loughner in the attempted killings of Rep. Gabrielle Giffords and two of her aides.
The shooting left six people dead and at least 13 others wounded Saturday, Jan. 8, at a Tucson, Ariz., shopping center.
The indictments for attempting to kill Giffords and two of her aides, Ron Barber and Pamela Simon, are expected to represent just the start of the federal case against Loughner, 22, of Tucson. He is expected to be charged in the six killings, but prosecutors continue to build those cases before pressing the charges.
"This case also involves potential death-penalty charges, and Department [of Justice] rules require us to pursue a deliberate and thorough process," U.S. Attorney Dennis K. Burke said in a written statement. "Today's charges are just the beginning of our legal action. We are working diligently to ensure that our investigation is thorough and that justice is done for the victims and their families."
Additional charges likely will be added later in superseding indictments, officials said.
Loughner could face life in prison if convicted of the attempted killings, according to a media release announcing the indictments.
"A conviction for the attempted assassination of a member of Congress carries a maximum penalty of life in prison, a $250,000 fine or both," the release said. "A conviction for attempted murder of a federal employee carries a maximum penalty of 20 years in prison, a $250,000 fine or both."
However, the judge who will hear the case is not bound to follow those guidelines in determining a sentence.
The initial indictment came as the FBI reviews surveillance video of the Tucson shooting rampage that shows the horrific scene in clear detail.
It also shows acts of heroism including federal Judge John Roll being gunned down as he tries to help another man.
On the surveillance video, according to people who have seen the tape, Roll, 63, pushes Barber to the ground in an attempt to get him out of the line of fire. Both men hit the ground. Barber survived his wounds, but Roll, who was shot in the back, did not.
The tapes are in the custody of the FBI and won't likely be released until trial.
The video obtained from the Safeway supermarket shows the area where Giffords was holding a "Congress on Your Corner" event. Authorities said Loughner is seen walking into the picture at 10:10 a.m.
According to officials who have seen the video, Loughner quickly moves around a table and shoots Rep. Giffords in her left forehead, just above her eye.
At the time the shot was fired, Loughner was within three feet of Giffords.
Then, Loughner reportedly turned to his left, faced the crowd, and continued the shooting, officials said.
Officials said the crystal-clear video footage shows muzzle flashes as the gun is fired.
Giffords survived the shooting and her condition has been upgraded to serious from critical.
In all, sources said Loughner allegedly fired 32 rounds before he was tackled by participants in Giffords' public event.
"I ran over to him and I knelt down and put my knee in his back, pulled out my cuffs and handcuffed him in place right there," said Pima County Sheriff Deputy Thomas Audetat. "As far as my recollection goes, he did not struggle with us at all."
Since his arrest, sources have described Loughner as calm, detached and often smiling.
The tapes may provide additional evidence that the assault was pre-meditated.
Loughner reportedly had ear plugs and was seen on tape talking calmly to a Safeway clerk in the moments before the shooting.
Sources said his parents have cooperated with the investigation and apparently had no idea what he had been planning.
ABC News' Leezel Tanglao contributed to this report.