MUMBAI, May 8 -- Days after a Mumbai couple and their two teenage daughters fell violently ill and died after a meal with relatives, police are now treating the case not as suspected food poisoning, but as a possible homicide or suicide pact. The twist came after the state-run Forensic Science Laboratory (FSL) submitted its report to police on Thursday. The report said traces of zinc phosphide, a highly toxic rodenticide, were found in samples of the viscera taken from all four deceased members of the family. Zinc phosphide was also found in watermelon samples taken from their house, a significant finding as all the four family members ate the fruit late at night after dinner with relatives. Deputy commissioner of police Pravin Mumde said t...