One of the poisons can be detected even from burnt bones

Bone, hair and nails are preserved in Heavy metals poisonings like arsenic, antimony, and thallium. Distribution of Arsenic in the body: * Arsenic is present in almost all tissues, and found in the greatest quantity in the liver, followed by kidneys and spleen. In cases, where the patient survives, it is found in the muscles (for months), bones, hair, nails and skin (Sulfhydryl groups in keratin) for years. Hair: Arsenic > 75 ug% - Poisoning. * Nails: Presence of > 100 ug% of arsenic - Poisoning.