Mumbai, April 10 -- Four men from Virar East, who were employed by a private contractor, died on Tuesday when they were working inside a 30-foot-deep sewage treatment plant. The workers - all in their 20s - were undertaking a clean-up operation at the plant in Virar West, and they likely died of suffocation, said the police. But the father of one of the victims alleged his son, an electrician, died of electrocution and not suffocation, and demanded a probe. Police have booked PloyCom, the contractor, for culpable homicide not amounting to murder....