Chocolate" colored post-mortem staining is seen in?
(HYPOSTASIS, POST MORTEM LIVIDITY, POSTMORTEM SUGGILLATIONS)
Lividity is a dark purple discolouration of the skin resulting from the gravitational pooling of blood in the veins and capillary beds of  the dependent parts of the body following cessation of the circulation.
The process begins immediately after the circulation stops, and in a person dying slowly with circulatory failure, it may be pronounced very shortly after death.
 This is due to the release of fibrinolysins, especially from small calibre vessels, e.g. capillaries, and from serous surfaces, e.g. the pleura. Clots may persist when the mass of clot is too large to be liquified by the fibrinolysin available at the site of clot formation.
In some deaths associated with infection and cachexia, this fibrinolytic effect may fail to develop, explaining the presence of abundant clot in the bean and large calibre vessels.
Thus, in cases of sudden death the blood remains spontaneously coagulable only during a brief period immediately following death; it then becomes completely free from fibrinogen and will never again clot. This incoagulability of the blood is a commonplace observation at autopsy.
The normal colour of areas of post mortem lividity is a cyanotic hue, but this description should not be used since it is misleading. The development of lividity is too variable to serve as a useful indicator of the time of death.
Carbon monoxide poisoning
KCN poisoning
Phosphorus poisoning
Potassium chlorate poisoning