A nine-year-old girl lies in the morgue. A member of Congress faces a lifetime of struggle to recover from a bullet in the brain. A city is bracing itself for a string of funerals as it tries to fathom the carnage.

But Trent Humphries says there is another innocent victim left by Jared Lee Loughner's killing of six people and wounding of 14 others in his assassination attempt against Congresswoman Gabrielle Giffords. It is his Tea Party movement and, more particularly, his family. The killings, he says, are evolving into a conspiracy to destroy his organisation and silence criticism of the government.

Humphries is the co-founder of Tucson's Tea Party, a movement besieged by accusations that its use of the rhetoric of armed resistance against political opponents played a role in the shootings.

The local sheriff, Clarence Dupnik, quickly pointed the finger at the growing vitriol, hate and anger directed against the government on talk radio and by Tea Party supporters in Arizona, where Democrats and liberals from President Obama to Giffords are portrayed as enemies of the people, un-American or Nazis.

Giffords herself warned that the Tea Party favourite, Sarah Palin, was "firing people up" with a campaign poster that put the Democratic party congresswoman in the crosshairs of a rifle.

Humphries is having none of it. "A lot have taken as gospel that the sheriff says that this was caused by talk radio, by Tea Party extremists, that that must be the case. I think it's done a lot of damage. It's given people the idea that somebody like my wife and I caused this murder. There's no evidence. And there's no evidence Sarah Palin caused this murder," he said. "The Democrats are using this opportunity to bludgeon their opponents. People don't want to hear that it was just some stupid, evil act that had no bearing in rationality. They want it to make sense."

There's no doubt that some people are blaming Humphries directly. He accuses the sheriff of prompting a string of accusatory emails. One said: "You people are responsible for the murder of a child, a judge and seven other innocents today. May you rot in hell."

Another accuser wrote: "It's time to change your message of hate. If not, get out of politics because the American people are not going to take it any longer. We want our country back."

Humphries, who runs a computer company and once ran for a seat in the state legislature but lost, is baffled. He says he too is grieving after one of his neighbours, Dorwan Stoddard, was killed shielding his wife from Loughner's bullets. She was wounded. But from the vigils outside the Tucson hospital where Giffords is being treated to the corridors of Congress, people are pointing the finger at the Tea Party. In his own city, that attention has focused on Humphries, whose organisation threw its support behind Giffords's opponent in November's election, Jesse Kelly.

Kelly, a former marine who served in Iraq, published a controversial campaign advert which included the lines: "Get on Target for Victory in November. Help remove Gabrielle Giffords from office. Shoot a fully automatic M16 with Jesse Kelly." Asked if that wasn't a kind of incitement, Humphries moves to his computer and finds a picture of Giffords brandishing an AK-47 several years ago.

"Guns are a big thing in Arizona. It's a culture. Giffords owns guns," he said. "You have President Obama telling a rally that we punish our enemies. You have him saying things like: if they bring a knife, we bring a gun. This is not something limited to the Tea Party movement."

Pressed on whether he was concerned when he heard Giffords's warning about Palin's use of gunsights and calls for supporters not to retreat but "reload" in fighting Democrats, Humphries did not retreat. "It's political gamesmanship. The real case is that she [Giffords] had no security whatsoever at this event. So if she lived under a constant fear of being targeted, if she lived under this constant fear of this rhetoric and hatred that was seething, why would she attend an event in full view of the public with no security whatsoever?" he said. "For all the stuff they accuse her [Palin] of, that gun poster has not done a tenth of the damage to the political discourse as what we're hearing right now. There are people who are genuinely confused, scared, and I understand it. But there are also people who are deliberately manipulating this event and tragedy for political ends."

Whether the accusations against the Tea Party are fair or not, Humphries acknowledges that the movement will feel the political fallout. "Do I think there's going to be blowback and people who are upset? Yes, in large part due to what the sheriff said. That's the tragedy for my family and what we're trying to do politically," he said. "There's a city election coming up next year and I'm sure this'll be used as a club and a hammer at that point to say: well, you're all just gun-crazy nuts and we can't listen to a word you say, you killed Gabby Giffords."

Humphries says also that one consequence is likely to be fewer guns in politics. "I'm pretty sure that for a little while yet you won't be seeing any politician holding an AK-47 or an M16. I'm pretty sure that's going to go away, and the last place that would go away is Arizona," he said.