An autopsy case performed by the author in 1986 had been gradually revealed to be a murder using aconite poisons. The puffer fish toxin was certified afterwards to be co-administered together with aconite alkaloids in this case. In order to investigate this murder case, animal experiments were done using mice to clarify the metabolism of aconitine and tetrodotoxin, and to examine the influences of tetrodotoxin on aconite poisoning. We also examined biological effects under the chronic intoxication of aconitine, and the elimination and degradation of aconitine in dead body. For this purpose we have developed technical methods using GC/MS and LC/MS for the quantification of these toxins in biological materials.