the.com/witness protection

means A government program that relocates and renames people whose testimony is dangerous enough to get them killed, trading their old identity for a chance at staying alive.

from Not an ancient word but a mid-20th-century legal creature — the term rose alongside formal U.S. federal programs (most famously housed under the Witness Security Program, nicknamed WITSEC, from the 1970s) built to shield mob and organized-crime witnesses whose testimony made them marked. 'Witness' traces back to Old English witnes, knowledge or testimony — someone who 'wot,' who knows. 'Protection' comes through French from Latin protegere, 'to cover in front,' pro- (before) plus tegere (to cover or shield). Put together, the phrase is almost embarrassingly literal: cover the one who knows, before someone silences them.