terminate with extreme prejudice

Etymology
1960s, US military intelligence and CIA, used publicly in 1969, in news coverage of Green Beret Case, further popularized in 1979 movie . Play on the term “terminate with prejudice” when an employee’s employment is terminated, meaning “will not rehire employee to same position in future” (i.e., prejudiced against rehiring), hence “terminate definitively, i.e., kill”.

Verb

 * 1)  To murder; to assassinate.
 * The government ordered the spies to be terminated with extreme prejudice: they did not want them to expose what they knew in a public trial.