When he was at last brought to justice it was proved that he had murdered something like a hundred children within a period of three years.

So, at least, runs one version of the story of this perverted being.
Naturally monarchs, constantly in need of funds, were interested in these alchemists.

Even sober England did not escape, and Raymond Lully, one of the most famous of the thirteenth and fourteenth century alchemists, is said to have been secretly invited by King Edward I.( or II.) to leave Milan and settle in England.

According to some accounts, apartments were assigned to his use in the Tower of London, where he is alleged to have made some six million pounds sterling for the monarch, out of iron, mercury, lead, and pewter.
Pope John XXII., a friend and pupil of the alchemist Arnold de Villeneuve, is reported to have learned the secrets of alchemy from his master.

Later he issued two bulls against "pretenders" in the art, which, far from showing his disbelief, were cited by alchemists as proving that he recognized pretenders as distinct from true masters of magic.
To moderns the attitude of mind of the alchemist is difficult to comprehend.