HUEYPOXTLA, Mexico - On Dec. 2, gunmen at a gas station commandeered a private truck that was carrying a heavy piece of cancer-treating machinery from a hospital in Tijuana to a storage facility for radioactive waste near Mexico City.

The theft set off global alarm bells, including an alert from the Vienna-based International Atomic Energy Agency, which described the highly radioactive cobalt-60 that had powered the missing equipment as "extremely dangerous."

Then, within two days, fears subsided that the material could be used for a "dirty bomb" if it fell into the hands of terrorists. Mexican officials announced that the material had been located and that the suspected thieves arrested.

Except in the village of Hueypoxtla, 35 miles northeast of Mexico City, where the hospital machinery and a tube containing the 60 grams of cobalt-60 came to rest in a cornfield, where they remained for days.

Villagers in Hueypoxtla wondered why no one came to claim the cobalt. Federal police kept a security cordon around an area that appeared to be close to a half-mile square in size. Farmers were blocked from tending their fields. No official offered an explanation. The lack of information unsettled townspeople.

They grew antsy, even irate.

At an open-air meeting one night this week they hounded Mayor Francisco Santillan.

"If there are 60 grams of cobalt around here, why don't they take it away?" asked Roberto Ramirez Bravo, a teacher who had grabbed a microphone.

As Santillan tried to answer, shouts of "Liar! Liar!" rang out.

Finally, late Tuesday, Mexico's Secretariat of Energy released a three-paragraph statement saying that authorities had, at last, succeeded in using a robot to put the cobalt-60 in a shielded container and removing it from the field.

In a telephone interview Wednesday, Mexico's nuclear safety director, Juan Eibenschutz, rejected complaints that authorities were slow in removing the cobalt-60, saying that they had done so "in world-record time." He said Mexico's rules on transfer of radioactive material were adequate and that any shortcomings that led to the robbery were the fault of a contractor, not the government.

"We'll have to see what measures we take, but the regulations are good," he said.

None of the six people detained in relation to the theft of the truck tested positive for radiation exposure, authorities say.

But doubts remain among villagers.

"The government will never tell us the truth," said farmer Maria de Lourdes Perez, 50, fretting over whether radiation would give cancer to the grandson walking at her side.