Police had been searching for Noppol for three days after he allegedly tricked 71-year-old Malai Chamgthong to accompany him on his motorbike, then raped her in the woods around Samakhee hill, 3 km from her home.
Noppol Bunsai (seated) has been arrested for allegedly raping his grandmother.
Horrified and scared, Malai had told her son Prayuth Bunsai, 42, about the incident and he had brought her to file the police complaint.
Police said Noppol confessed to the attack, claiming he was high on drugs and full of lust. He told Malai her other grandson had been in an accident and she came with him on the bike after midnight.
Malai told police Noppol had threatened to abuse her again and even kill her if she told anyone what had occurred.