Charles Ellicott Commentary Mark 6:27

"And straightway the king sent forth a soldier of his guard, and commanded to bring his head: and he went and beheaded him in the prison," — Mark 6:27 (ASV)

An executioner.—St. Mark uses a Latin word, speculator, a word which, originally meaning “watchman” or “sentinel,” had come to be applied by Latin writers of the time specifically to soldiers employed, as in this instance, as couriers or messengers (Suet. Caligula, c. 44; Tacit. Hist. xi. 73).