NEW YORK — A trove of internal Arizona state police documents released by a hacker group last week contains a confidential federal report that contradicts claims by Arizona politicians, including Gov. Jan Brewer and Sen. John McCain, that violence tied to drug trafficking and illegal immigration from Mexico is on the rise in the state.

Throughout 2010, Brewer claimed that cartel-related violence was increasingly spilling over into Arizona cities and towns. Most infamously, she stated that Arizona law enforcement had found bodies decapitated by cartels in the Arizona desert.

"We cannot afford all this illegal immigration and everything that comes with it, everything from the crime and the drugs and the kidnappings and the extortion and the beheadings and the fact that people can't feel safe in their community," Brewer told Fox News in June 2010.

Brewer retracted the claim about beheadings after it was questioned by southern Arizona police and coroners. But she continues to maintain that a rising tide of violence is spilling into the state from the increasingly bloody situation in Mexico.

Brewer has repeatedly raised the specter of cross-border violence as justification for the state's controversial immigration law, SB 1070, which requires local police to demand immigration documents from those they suspect of being in the country illegally.

"We cannot delay while the destruction happening south of our international border creeps its way north," Brewer said before signing the bill last year.

Sen. John McCain has made similar claims about border violence.

"I am gravely concerned with the continued and apparently growing violence along our border with Mexico," he wrote to Department of Homeland Security Secretary Janet Napolitano last March.

"The federal government must do all it can within its power to curb this violence and protect its citizens from criminals coming across the border from Mexico," he said.

Yet the hacked report, by the Department of Homeland Security's Office of Intelligence and Analysis, finds no signs that significant violence in Mexico is spilling across the border into Arizona.

The agency "lacks information that indicates Mexican traffickers have directed any killings in Arizona" between 2008 and 2009, the report states, in a section titled "Violence Rising in Mexico, but Not in United States."

The report also notes that Arizona's murder rate plunged by 20 percent statewide between 2008 and 2009. It cites one murder — the 2010 shooting of an Arizona rancher — as "one of the few homicides that clearly have a cross-border connection."

"Occasional reports of cartel plans to target U.S. law enforcement officers so far have come to naught," it continues.

Also documented in the report is a 50 percent drop in border apprehensions of illegal immigrants in Arizona between 2003 and 2009. In the Yuma region near the California border, apprehensions dropped by 95 percent since 2005, "almost certainly reflecting improvements to the border fence."

The report is not classified, but is marked "law enforcement sensitive" and is not for public distribution. Its conclusions about border violence are similar to other recent analyses of publicly available data conducted by Arizona media outlets and policy groups.

Press officers for Brewer and McCain did not respond to requests for comment.

The trove of documents containing the confidential report was obtained by Lulz Security, an anonymous hacker group that has claimed responsibility for a variety of other Internet attacks over the past year.

The documents included the names, addresses and telephone numbers of several border agents, but an Arizona state police spokesman said it appeared that "no records related to ongoing investigations or other sensitive matters have been compromised."

The hackers obtained the documents by breaking into the email accounts of state police officers.

The majority of the released documents describe routine police business, although some detail potential threats to the state from violent fugitives, drug traffickers, terrorists and homegrown extremists.

Confidential internal reports and email messages also note the regular presence of immigration vigilantes on the border. In one instance, two active-duty Marines were encountered by border patrol agents on private land near the Arizona-Mexico border.

"The subjects, armed with pistols and at least one M4 rifle, were dressed in full desert camouflage uniforms, similar to those of the United States military," states the 2008 report by the Arizona High-Intensity Drug Trafficking Area investigative support center.

"They stated they were not members of the Minutemen, but paid contract employees who 'get the job done' and 'were not just volunteers.' They possessed valid United States Marine Corps identification cards."