A person was found dead with bluish green frothy discharge seen at the angle of mouth and nostrils. What is the most likely cause of his death?

This man is showing features of copper sulphate (blue vitriol) poisoning as indicated by bluish green discharge from mouth and nostrils. Main features of copper sulphate poisoning are vomiting, abdominal pain and sometimes diarrhea. Vomitus usually have a bluish green hue. Later patients develop renal and hepatic damage with hemolytic anemia. Fatal dose of copper sulphate is 30gm. Treatment: involves chelation with penicillamine or EDTA or BAL.