In which of the following condition nails and hairs are commonly preserved?

In chronic arsenic poisoning, arsenic is seen in the muscles for days, in the bones and in the keratin tissues, hair, nails and skin for years. It replaces phosphorus in the bone where it may remain for years. It can appear in hair and nails within hours of ingestion. Neutron activation analysis and atomic absorption spectroscopy helps in estimating concentration of arsenic in hair, nails, bones, etc. Ref: The Essentials of Forensic Medicine and Toxicology by K S Narayan Reddy, 27th edition, Page 423.