The Supreme Court upheld the death sentence passed by the two lower courts on the three defendants the headlining murder of a restaurant waitress in 2016.
The court's ruling was read out at Talingchan Criminal Court on Tuesday.
Facing the death sentence are former Lt Chaiyut Benjachart, 44, former Pol Sen Sgt Maj Samat Saengsin, 51, and former Pol Sgt Maj 1st Class Phanumet Meela.
Prosecutors previously told the courts that the three defendants were hired by former Pol Col Amnuay Pongsawat, then superintendent of Ban Pong police station in Ratchaburi province, and Sanong Somsit to abduct Supaksorn "Ying" Polthaisong, a restaurant waitress. The woman was said to be a tomboy and to have become romantically involved with a songstress that Pol Col Amnuay had been dating.
