





The federal police force said it provided the robot. Its statement added that 100 federal police, marines and local officers were still guarding the area.

Eibenschutz said a farmer was being checked at a hospital after showing signs of radiation exposure. The man, who lives in the nearby farming town of Hueypoxtla, told authorities that he handled the material after finding it in the field and started feeling sick soon after.

The cobalt-60, which was from obsolete medical equipment used in radiation therapy, was being transported to a waste facility by a truck that was stolen at gunpoint early Dec. 2 when the driver stopped to rest at a gas station in Hidalgo state.

Two days later, authorities found the truck abandoned in neighboring Mexico state. The thieves had removed the cobalt-60 from its protective container and left it nearby in the field about a kilometer (a half a mile) from Hueypoxtla, a town of about 4,000 people. Officials have said the material posed no threat to the town, saying it was dangerous only in close proximity.

On Monday, a federal judge ordered five people held for 40 days under a form of house arrest pending possible charges.

Four of the detainees are suspected in the theft of the truck and the fifth was allegedly a possible buyer of the stolen vehicle, said an official with the Attorney General's Office, who spoke on condition of anonymity because he was not authorized to speak to the media.

The farmer exposed to radiation is not a suspect in the case, authorities said.