Police have questioned a security guard working at the steam power plant in Prachin Buri's Sri Maha Phot district where a bulky tube containing radioactive caesium-137, a highly hazardous isotope, went missing.
As the search for the missing metal tube has continued for over a week now, the provincial administrative office has doubled the reward being offered to anyone who provides information leading to its discovery. The reward is now set at 100,000 baht.
The security guard told investigators during questioning that he had taken a pickup truck on Feb 11 to be washed at a car care shop, but there was no heavy metal tube in the truck bed as the car care shop people claimed.
The police let the guard go after the interrogation.
Earlier, Somchet Rasimin, the shop owner, told police he remembered seeing a guard visit his shop for a car wash service. The owner spotted a metal tube in the bed of his truck, which looked similar to the one he had since seen in news reports.
When police showed them a picture of the missing tube, other staff said the same. They also tried moving it, but it was too heavy, they said.
"We usually remove things from the truck bed so we can wash it with foam and water; but that tube, sitting in the right corner, was heavy and didn't budge," said Mr Somchet.
The guard was still wearing his uniform when he arrived at the car care shop at about 8am that day, said Mr Somchet.
Kitkawin Aramrun, head of the Emergency Operation Centre of the Office of Atoms of Peace, said the search is continuing mainly inside the power plant and places nearby.