Like Norman Bates, with a Baton

For Halloween, Creepy Conductors Dept., Part I:

In 1956, conductor Eugene Goossens's brilliant career was brought down by scandal. Returning to Sydney from London, customs officials found over a thousand pornographic photographs, sealed in envelopes marked "Brahms" and "Beethoven." They also found a mask, and letters linking Goosens to Rosaleen Norton, the notorious "Witch of Kings Cross," who initiated Goosens into her circle, which practised ritual acts of sexual black magic.

Creepy Conductors Dept., Part II:

Swiss conductor Michel Tabachnik has gone on trial a second time for alleged involvement in the deaths of members of a doomsday cult. Tabachnik is charged over the deaths of 16 people who were found in a forest in the French Alps in 1995. Prosecutors say he incited members of the Order of the Solar Temple to commit mass suicide. Tabachnik denies the charge, and he was cleared by a French court in 2001, but prosecutors appealed against the verdict. Tabachnik studied under Pierre Boulez and held orchestral posts in Canada, Portugal and France.

Of course, some musicians might say all conductors are mass-murderers, in a manner of speaking... ;-)