Mathieu Orfila

Mathieu Joseph Bonaventure Orfila (Catalan: Mateu Josep Bonaventura Orfila i Rotger) (24 April 1787 – 12 March 1853) was a Spanish toxicologist and chemist, the founder of the science of toxicology.

If there is reason to believe that a murder or attempted murder may have been committed using poison, a forensic toxicologist is often brought in to examine pieces of evidence such as corpses and food items for poison content. In Orfila's time the primary type of poison in use was arsenic, but there were no reliable ways of testing for its presence. Orfila created new techniques and refined existing techniques in his first treatise, Traité des poisons, greatly enhancing their accuracy.

In 1840, Marie Lafarge was tried for the murder of her husband using arsenic. Mysteriously, although arsenic was available to the killer and was found in the food, none could be found in the body. Orfila was asked by the court to investigate. He discovered that the test used, the Marsh Test, had been performed incorrectly, and that there was in fact arsenic in the body, allowing LaFarge to be found guilty.