A 40-year-old man was stabbed to death by his sister's former husband in east Delhi's Kalyanpuri area on Saturday, police said. The incident happened in Block 44 of Kalyanvaas, they said, adding the deceased has been identified as Neeraj. According to police, the victim's relatives have alleged that the former husband of Neeraj’s sister, who had come from Uttarakhand, was behind the incident.