extortionist (n.)

"the act of extorting, the act or of wresting anything from a person by force, duress, menace, authority, or any undue exercise of power, oppressive or illegal exaction," c. 1300, from Latin extortionem (nominative extortio) "a twisting out, extorting," noun of action from past-participle stem of extorquere "wrench out, wrest away, to obtain by force," from ex "out" (see ex-) + torquere "to twist" (from PIE root *terkw- "to twist").

word-forming element meaning "one who does or makes," also used to indicate adherence to a certain doctrine or custom, from French -iste and directly from Latin -ista (source also of Spanish, Portuguese, Italian -ista), from Greek agent-noun ending -istes, which is from -is-, ending of the stem of verbs in -izein, + agential suffix -tes.

Variant -ister (as in chorister, barrister) is from Old French -istre, on false analogy of ministre. Variant -ista is from Spanish, popularized in American English 1970s by names of Latin-American revolutionary movements.