MUMBAI, June 4 -- A four-year-old boy was allegedly beaten to death by his mother's partner and his body dumped in a drain in Bhayander, with the child's mother helping cover up the crime, police said on Monday. The accused, identified as Rama Singh, 30, and her lover Shambhu Sharma alias Nepali, were arrested by the Kashigaon police after a post-mortem report contradicted Singh's claim that the child had accidentally fallen into a drain while she was sleeping on Sunday night. Police said Singh had separated from her husband some time ago, and was living with her son in a chawl in Mira Road, Kashigaon, . The victim, identified as Ganesh Singh, was found dead in a drain on Monday morning. His mother, Rama, initially told police that she was asleep when the child allegedly wandered out and fell into the drain. Based on Singh's statementpolice registered an accidental death case. However, investigators grew suspicious after noticing injuries on the boy's body that appeared inconsistent with a fall. According to police, the boy had several bruises on his body as well as there were few scratches on his shoulder and back. A post-mortem examination later confirmed that the child had suffered multiple assault injuries. The medical findings prompted a detailed investigation, during which officers uncovered Rama Singh's relationship with Shambhu Sharma, alias Nepali, a senior police officer from Kashigaon police station said. "The child had become an obstacle in their relationship; as a result, Sharma would constantly physically abuse the boy," said the police officer. According to police, Sharma routinely assaulted the boy and allegedly beat him on Sunday, leading to his death. Singh was allegedly aware of the abuse and later joined Sharma in disposing of the body to destroy evidence. Police have booked the couple for murder and destruction of evidence under the relevant sections of the Bharatiya Nyaya Sanhita....