Federal prosecutors have announced new charges against Jared Lee Loughner in the attempted assassination of Rep. Gabrielle Giffords.

They accuse him of killing six people and wounding 13 others who were exercising the fundamental American "right to meet freely, openly and peaceably with their member of Congress."

U.S. Attorney Dennis Burke called the 49-count indictment returned Thursday against Loughner "comprehensive and … solid, and covers all the murdered and injured victims" who were at the political event held by Giffords outside a northwest-side grocery store.

"There are no distinctions at all between the victims," Burke said, adding that they "were exercising one of the most precious and fundamental rights of American citizens."

The indictment charged Loughner in the murders of U.S. District Judge John Roll and Giffords aide Gabe Zimmerman. Four other people who were not federal workers also died in the Jan. 8 attack, including 9-year-old Christina-Taylor Green, and 13 others were wounded.

He also was charged with causing the death of a participant at a federally provided activity; injuring a participant at a federally provided activity; and using a gun in a crime of violence, stemming from the wounding of 10 people who didn't work for the federal government.

Loughner had pleaded not guilty to earlier federal charges of trying to assassinate Giffords and kill two of her aides.

His attorney, Judy Clarke, didn't immediately return a call and an e-mail to her office Friday.

Federal prosecutors haven't yet said whether they will seek the death penalty against Loughner. But legal experts believe it's a virtual certainty.

Burke said that because Loughner is eligible for the death penalty if convicted of some of the charges, the U.S. Attorney's Office is pursuing "a deliberate and thorough process" in prosecuting the case.

Loughner will likely face state charges in the attack as well, but will be tried first in federal court before any prosecution begins on state charges. Federal and county prosecutors said federal law requires state prosecutions to be suspended while a federal case is pending.

Loughner is scheduled for a court hearing in Tucson on Wednesday, when he will be arraigned on the new charges.

A day after the shootings, prosecutors filed a complaint in court charging Loughner with trying to assassinate Giffords, attempting to kill two of her aides, and killing Roll and Zimmerman. Those charges were later replaced by federal indictments that mirrored the same charges.

In many criminal cases, prosecutors will often file charges themselves without a grand jury indictment, but will later replace those charges with an indictment.

It was not known why the charges against Loughner weren't contained in one indictment.