Violence along the border with Mexico will likely increase this year as the administration bolsters Border Patrol staffing and adds more fencing and technology to catch illegal immigrants, Homeland Security Secretary Michael Chertoff has said.

Recently, U.S. Border Patrol Agent Luis Aguilar, 32, was killed in California's Imperial Sand Dunes recreation area, run over by suspected drug smugglers as he was laying down a spike strip to stop their fleeing Hummer.

The Los Angeles Times reports that Aguilar's death has drawn attention to escalating violence on both sides of the U.S.-Mexico divide, which Chertoff and other administration officials attributed partly to heightened border security measures.

"Experience shows that the more successful you are in putting pressure on criminal organizations, the more violent they will become in fighting back," Chertoff said. "The sad, tragic fact is that the increase in violence is very consistent with other metrics we've had that show we're getting increased success with stopping the flow across the border."

In an interview with The Times and the Associated Press, Chertoff and Border Patrol officials said the agency considered the agent's death a murder -- the first since 1998 of a Border Patrol agent -- and was working closely with Mexico to investigate. The Hummer's driver appeared to swerve not just to avoid the spike strip, but to "hit the agent intentionally," one witness said.

Chertoff and other officials said Aguilar's death highlighted a need to continue such initiatives as a fence.

Several border groups have sharply criticized Homeland Security's plan to build a border fence on private land. Many residents, mayors and business owners also object to Chertoff's announcement that if necessary, his agency will seize land from unwilling property owners in order to continue construction.