Thanjavur police on Tuesday arrested two persons, who had reportedly sexually assaulted and murdered a woman. Sources said that S Kanagavalli (33), a resident of Ammapettai, used to take cattle for grazing. On Monday evening she did not return, her parents found her dead with injuries and alerted Ammapettai police. Police secured one Periyasamy (28) on suspicion and he confessed that he along with his friend Sathish (22) kidnapped and sexually assaulted her resulting in death.