A Naxal couple with acollective reward of Rs 13 lakh on their heads on Saturday surrendered in Chhattisgarh's Rajnandgaon district, police said.Gaindsingh Kovachi (35) and his wife Ramsheela Dhurve (22) turned themselves in before senior police officials, citing disappointment with the hollow Maoist ideology and exploitation of tribals by senior ultras, an official said.Kovachi, who was active as Mohla-Aundhi area committee secretary of the Maoists, had joined the outlawed outfit in 2006, he said."Over three dozen cases related to Naxal incidents, including murder, loot and dacoity, were registered against him in different police stations of the district. He carried a reward of Rs 8 lakh on his head," the official said.Dhurve, who was a member of area committee and zonal medical team and had a reward of Rs 5 lakh against her name, used to provide treatment to ultras injured in encounters with security forces and ailing cadres, he said."They were given Rs 10,000 each as encouragement money and will be provided further assistance as per the surrender and rehabilitation policy of the state government," he said.