The worker, a Myanmar national identified only as Kala, said yesterday his boss, Pol Col Supat Laohawattana, a doctor with the Police General Hospital, ordered him to bury the two corpses found in the orchard on Thursday and yesterday.
Kala was questioned yesterday by Tha Mai Ruak police while waiting for the surrender of Pol Col Supat, who did not show up.
In his statement, Kala said he had worked for the doctor for more than 18 years.
He said he was forced to work hard without pay and was given little to eat.
The man was living in a eucalyptus plantation in Ban Wang Khao San of Tha Yang district. His right arm has been amputated and his legs are crippled.
He told Pol Lt Col Preecha Rodkhongthee, a deputy chief of the Tha Mai Ruak police station, that he lost his arm because Pol Col Supat had forced him to insert it into a corn grinding machine after complaining he was working too slowly.
Kala also said he was crippled because his boss ordered him to climb coconut trees and one time he fell down and severely injured his legs.
He told police that Pol Col Supat often turned violent when he was dissatisfied with his workers.
The doctor punished them in a variety of ways, ranging from hitting them with a wooden stick to cutting their ears off, according to Mr Kala's statement.
About two years ago, Kala said, Pol Col Supat was so upset with the performance of two of his workers that he killed one of them by forcing them to swallow pesticide.
Around the same time, he saw his boss shoot dead another of the workers, Kala said, adding that he wanted to run away but dared not out of fear that he might be caught by the boss and end up murdered like the others.
The bodies police found buried in the doctor's orchard were those of one his fellow workers, Kala said.
He claims Pol Col Supat once told him to put two corpses into empty fertiliser bags, dump them into a pond in the pineapple orchard, and then cover the pond with soil using a tractor.
Police dug up the human remains after a tip-off that the bodies of husband and wife Samart Noomjui and Orasa Kerdsap could be buried in the doctor's orchard.
Yesterday, police raided the doctor's orchard again and continued digging with a backhoe.
They found the remains of another body.
Samart's father Sawang Noomjui, who was at the scene, said the remains could be those of his son.
Before Thursday's search, Mr Sawang, 55, had lodged a complaint with Nonthaburi police after Samart and Orasa's pickup truck was found in a deserted house in Nonthaburi.
The house was later identified as belonging to a relative of Pol Col Supat.