A 40-year-old teacher was found dead, her weighted body dumped in a pond, in Phetchaburi on Thursday night, about two weeks after she was reported missing.
A 38-year-old soldier, her close friend, has been charged with her murder.
Sgt Maj 1st Class Surin Pramnoi admitted to having strangled Wanida Omthet, police said on Friday.
Wanida was a teacher at a school in Kaeng Krachan district. She and her pickup truck had not been seen since the night of May 26. Relatives filed a missing person report with local police.
Police said that after questioning her relatives and friends, investigators focused their attention on Sgt Maj Surin.
He admitted to having quarrelled with her in a fit of jealousy. Investigators later found the teacher’s vehicle at another person's house. The house owner said the soldier pawned it for money.
He did not know what to do with the body, so he dumped it in the pond in a banana field behind his house.
Forensic police and rescue workers retrieved the body from the pond around 10.30pm on Thursday. The body was weighted down with bricks and railway steel, Thai media reported.
The body had partially decomposed in the water, but forensic examiners found signs of knife wounds to her chest, stomach and back, police said.