Source of anthrax pinpointed to Texas ranch.(The Dallas Morning News)

HEBBRONVILLE, Texas _ Robert Fulbright surveyed the land his grandfather settled in 1906, thick with mesquite and prickly pear cactus. Not the lushest part of Texas, but fine country for raising cattle, he said _ if you don't mind the anthrax.

"They fever so bad, they look like they've been dead longer than they've been dead," he said, recalling an outbreak in 1975 that claimed at least 100 cattle. He spent much of the summer burning carcasses. "Fire's the only thing I know that'll kill it for sure. It's a nasty son of a gun."

A killer lurks beneath the soil of Jim Hogg County, awaiting the right combination of rain and sun and hungry cattle to come to life.

And this is no ordinary killer. The anthrax that was sent to the Senate and that killed a Florida tabloid editor, a handful of postal workers, an elderly Connecticut woman and a New York hospital worker, was traced in February to this remote corner of South Texas _ to a 14-month-old cow that died on a vast and lonely ranch an hour's drive from the Rio Grande.

Veterinarian Michael Vickers took tissue samples from the cow, never imagining that the bacteria they contained would end up wreaking havoc two decades later. He was as shocked as anyone to learn of his connection to the attacks. But having struggled to contain outbreaks that claimed 30 cows in a day, it made some sense.

"This is a very lethal strain of anthrax that we see down here," he said. "It's very, very severe, and it kills with extreme prejudice."

No one is sure where the Jim Hogg anthrax came from. Perhaps the conquistadors brought it to the Americas, or it hitched a ride on some Chinese wool a half-century ago. The FBI, the CIA and others ...