Border Wars: Patrol Told to Scare Away Immigrants, Not Arrest Them?

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An Arizona sheriff's explosive allegation that Border Patrol agents are "chasing people away" rather than arresting illegal migrants has drawn a scathing rebuke from top Homeland Security officials.

Cochise County Sheriff Larry Dever said in an interview on Fox News last week that a senior border patrol agent told him agents were under orders to reduce border arrests during specific reporting periods.

"The senior supervisor agent is telling me about how their mission is now to scare people back," Dever said. "I had to go back to my guys and tell them not to catch anybody, that their job is to chase people away. They were not to catch anyone, arrest anyone. Their job was to set up posture, to intimidate people, to get them to go back."

Border Patrol Chief Michael Fisher sent a letter to Dever Tuesday strongly refuting his claim, which appears to have been based on a single, unidentified source.

"That assertion is completely, 100 percent false," Fisher said in the letter obtained by ABC News. "And most disturbingly, it unfairly casts a negative light on the hard work done each day in service to the nation and at risk to themselves by the men and women of the Border Patrol."

"That it comes from a fellow law enforcement official makes it especially offensive," he wrote.

Fisher said the Border Patrol's policy is to apprehend and arrest every illegal border crosser, and he invited Dever to ride along with border agents to see the reality of the work they do.

"It is possible notwithstanding your position, that you may remain unaware of the scope of our enforcement efforts across the Southwest Border, particularly in Arizona," he said.

But Dever insists the information he received is credible -- and alarming.

"I do not make this stuff up," he said in a statement following the interview. "I can unequivocally say what I have told you comes from Border Patrol agents who work the problem every day and other federal government officials from various organizations."

Political posturing is what Homeland Security Secretary Janet Napolitano, who oversees the Border Patrol, has called attempts to discredit the agency's work and characterize conditions along the border as out of control.

"It is simply inaccurate to state, and too many have, that the border with Mexico is overrun or out of control," she said in a speech last week.

"This statement I think sometimes is made to score political points. You know, it's wrong. It's just plain wrong. Continuing to make these assertions in the face of everything that is happening and everything that has been done not only has negative consequences for our own border communities but it also disrespects the efforts of the law enforcement men and women on that border."