U.S. Attorney Dennis Burke said the investigation was in its early stages, and this was just the initial indictment of Loughner, who is expected to be charged with two additional counts for the murder of federal judge John Roll and Giffords aide Gabe Zimmerman (in addition to state murder charges for the non-federal employees killed in the massacre).
"We have made considerable progress in a short period of time," Burke said. "This case also involves potential death-penalty charges, and Department rules require us to pursue a deliberate and thorough process. Today's charges are just the beginning of our legal action, and we are working diligently to ensure that our investigation is thorough and that justice is done for the victims and their families."
Because the office is pursuing the death penalty against Loughner for the murder of Roll and Zimmerman, their case must first go through a process with DOJ's Capital Review Committee.
The feds first filed a complaint against Loughner the day after the shootings.
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, DOJ said, while a conviction for attempted murder of a federal employee carries a maximum penalty of 20 years in prison, a $250,000 fine or both.
Six people were killed and 13 others wounded in the Jan. 8 attack.