Another 65 rare tortoises have been stolen from the Bang Phra Waterbird Breeding Research Centre of the National Parks, Wildlife and Plant Conservation Department in Chon Buri's Si Racha district.
Police investigators believe it was an "inside job".
Adisorn Nuchdamrong, deputy director-general of the department, said 62 Indian star tortoises (scientific name: Geochelone elegans), each worth 1,000-2,000 baht, and three radiated tortoises (Astrochelys radiata), each worth about 20,000 baht, were stolen from the breeding centre around 3am on Dec 24.
Security camera footage showed two men, each wearing a knitted hood and a pair of gloves, entering the centre around that time. A complaint was subsequently filed with Si Racha police.
Mr Adisorn said later that police had questioned many staff at the breeding centre, including its new chief Padet Laithong.
The information collected pointed to the theft being carried out by someone on the staff.
Security camera footage showed a tattoo on one of the burglars, who was wearing shorts. He hoped this would led to an early arrest.
In June, six uniflora tortoises and 72 radiated tortoises disappeared from the centre. The culprits have not been caught.
Mr Adisorn said he was surprised the thieves did not take the only uniflora tortoise remaining at the centre, instead opting to steal geochelone tortoises, which were less valuable to collectors. Madagascar's uniflora is the rarest species of land tortoise, with specimens selling for the equivalent of 1 to 2 million baht each.
The latest theft of tortoises occurred on two days before National Wildlife Protection Day, Dec 26.