Police said the accused allegedly trailed Ayush Kashyap – son of local Congress leader Samelan Kashyap of Karhi village -- as he returned home on April 24. (Express photo) A month after the 18-year-old son of a Congress leader was shot dead in Chhattisgarh’s Sakti district over an alleged illegal sand-mining rivalry, police have arrested four men — including the alleged key conspirator. Police said the accused allegedly trailed Ayush Kashyap of Karhi village as he returned home on April 24, changed clothes to mask their identity, forced their way into his house and locked his parents in a room before shooting him dead. His 16-year-old brother was also shot but survived. The gang had also broken nearby CCTV cameras before the attack. Ayush’s father, Sammelan Kashyap, a local Congress leader, had alleged at the time that his son was killed over a business rivalry linked to illegal sand mining in the area. Police now say the investigation has confirmed that angle.…