Capo: (n) The head of a branch of an organized crime syndicate. (wolfram)
(n) a device used on the neck of a stringed (typically fretted) instrument to shorten the playable length of the strings, hence raising the pitch. (wikipedia)
Merriam Webster describes the etymology of Capo as:
Italian, head, chief, from Latin caput
First Known Use: circa 1952
(Kapo), trustee, an SS appointed prisoner who was the head of a labor squad. He or she retained this privileged position by terrorizing subordinate prisoners.
The Capos were an instrument of the camp regime of humiliation and cruelty, and their role was to break the spirits of the prisoners.
The Capos had warm clothing, enough to eat and lived in a reserved section to the prison barracks. In many instances Capos who mistreated prisoners were put on trial after the war.
Etymonline defines Italian origin of the term thusly:
“pitch-altering device for a stringed instrument,” 1946, short for capo tasto (1876), from Italian, literally “head stop” (see head (n.)).