Yesterday marked the first anniversary of the murder of Arizona rancher Rob Krentz by an illegal alien. His death was especially shocking because Krentz had no involvement with the illicit traffic across our border with Mexico — previously, the violence had been almost completely confined to, for instance, illegal aliens held for ransom by their smugglers, or drug dealers fighting over their contraband, or law-enforcement officers upholding the laws of the United States.

But Krentz was just an ordinary rancher who happened to be in the path of the increasingly dangerous flows across our border. His murder has had far-reaching effects. Though the legislation was already in the works, the killing helped impel the passage of SB 1070, Arizona’s landmark anti-illegal-immigration measure, which, in turn, led to the infamous Justice Department lawsuit against Arizona.

In an attempt to manage the political fallout of Krentz’s murder and the DOJ lawsuit in the leadup to the November elections, the Obama administration deployed National Guard troops to the border, though purely in a support capacity. (They’re preparing to leave in June.)

Krentz’s murder also led the administration into Baghdad Bob–style denials of reality, most notably homeland-security secretary Janet Napolitano’s assertion that “the border is as secure now as it has ever been.” Since she said that, Border Patrol agent Brian Terry was murdered west of Nogales by smugglers, and a drug dealer in suburban Phoenix was beheaded for stealing from a Mexican cartel.

This highlights a development that was repeatedly confirmed to me by locals when I toured the Arizona border earlier this year — numbers of people sneaking across are indeed down, but the danger level is up. A Border Patrol spokesman made the same point to a Washington Post reporter last month:

The number of Border Patrol agents has doubled since 2004, and the danger they face when stopping potential illegal immigrants has increased “exponentially,’’ said Mark Qualia, a spokesman for U.S. Customs and Border Protection.

“In the 1990s, you’d be catching migrant workers, average Joes coming here to seek jobs,” he said. “There was very, very rarely any altercation.’’

Now, Qualia said, agents are more likely to encounter people with outstanding warrants for drug trafficking and other crimes.

“They are much more desperate, and they have a tendency to be a lot more combative,” he said.

This increased danger has led to perhaps the most interesting development in the year since Krentz was murdered: his fellow ranchers have gotten organized in demanding real border control. Before March 27, the Arizona Cattlemen’s Association was just a trade group like any other — representing the interests of the state’s beef-producing families to the legislature, litigating water rights, running quality-certification programs, etc. But with the murder of one of its own last spring, the organization put together the Restore Our Border (R.O.B.) plan, named after Krentz and designed to prevent similar outrages against their members and other Arizonans. The cattlemen lobbied the legislature, and a resolution endorsing the plan was passed by the state senate last month and is now before the house.