The Criminal Court earlier ordered capital punishment for Tanu Hinkaew who was charged with masterminding the premeditated murder of Charoen Wat-aksorn, leader of an environmental conservation group protesting construction of the Bo Nok power plants in Prachuap Khiri Khan province, 280 km south of Bangkok.
In its verdict today, the Appeals Court said there was insufficient evidence to charge Mr Tanu. He smilingly left the courthouse later without talking to the media.
Four other suspects were implicated in the case. Two of them, identified as Saneh Lekluan and Prachuab Hinkaew, were gunmen allegedly hired to shoot Charoen. Both died earlier in prison.
Two additional suspects, Manote and Chua Hinkaew, were acquitted in the Criminal Court.