The four other former policemen are Niran Taemchuay, Rangsiman Sukkaew, Panang or Chakrin Duangkamol and Apisak Polsawat, all holding the rank of police sergeant major.
The colurt was told the five arrested a husband and wife on a drug charge and took them to the 42nd BPP headquarters in Nakhon Si Thammarat province where they were beaten and tortured. The five demanded 250,000 baht from them in return for the drug charge being dropped.
The court found the five guilty as charged and sentenced gang leader Nat to seven years and the other four to five years each in prison, with no suspension of sentence.
Nat had earlier been found guilty and sentenced to imprisonment for other extortion cases, arresting people on the pretext of laying drug charges.
All were dismissed from the police force.