Giffords had been target of violent threats
In August 2009, an attendee at a Giffords town-hall meeting dropped a handgun, leading Giffords's staff to call the police. "We have never felt the need before to notify law enforcement when we hold these events," her spokesman said at the time.
That same month, Sarah Palin's political action committee posted a map of the US, showing the locations of the 20 Democratic members of Congress, including Giffords, it was targeting for defeat. Each location was marked by an image of a gun crosshairs.
Palin's camp dismissed charges that she was encouraging acts of violence, saying she had spoken out against violence. But Giffords herself was one of many who spoke out against the image, telling MSNBC: "When people do that, they've got to realize there's consequences to that action."
In June, the campaign of Giffords' Republican opponent in this year's midterms, Jesse Kelly, placed an ad that read: "Get on target for victory in November/ Help remove Gabrielle Giffords from office/ Shoot a fully automatic M16 with Jesse Kelly."
The website for Kelly, a former US Marine, depicted him with holding an automatic weapon.
