C.J. Karamargin confirmed Friday that the Democratic politician was told in late July the names of the dead, including her aide Gabe Zimmerman; U.S. District Judge John Roll, a close friend; and 9-year-old Christina-Taylor Green, the Arizona Republic reported.
Giffords has been recovering from a gunshot wound to the brain from the Jan. 8 shooting that killed six people and wounded her and 12 others. The man charged in the rampage, Jared Lee Loughner, was sent to a federal prison facility in Springfield, Mo., after a federal judge concluded he was mentally incompetent to stand trial on 49 charges.
Her loved ones had been keeping the extent of the tragedy from her until she was strong enough to handle it. Husband Mark Kelly said in June that Giffords knew how many people were killed or wounded but wasn't aware that Zimmerman and Roll were among them.
"She was deeply saddened by it," said Karamargin, who is leaving Giffords' staff for a job with Pima Community College.
Giffords received the news just days before her surprise Aug. 1 appearance on Capitol Hill to vote on the federal debt ceiling.
Giffords was meeting with constituents in the parking lot of a Tucson grocery store when she was shot.
This month, Giffords gave her personal condolences to Ross Zimmerman, Gabe's father, during a brief telephone conversation, the paper reported .
"She still has some trouble with language, but there is no question that she can get her point across and her comprehension is 100 percent," Zimmerman told the paper. "It was Gabrielle - it was nice to talk to her."