Career
His brothers, particularly Peter and Thomas Killigrew, had been engaged in piracy off the Irish coast during Edward's reign. Together with his father, John opposed the Catholic Queen Mary I (1553–1558) and her husband, Philip II of Spain, and used his fleet of ships to keep the Protestant exiles in France abreast of political developments and to attack Spanish shipping in the Channel. In 1556, he was imprisoned by Mary with his father in the Fleet, but released after three weeks. Peter Killigrew maintained his activities in opposition to Mary's reign, while his brother Henry Killigrew remained an exile abroad.
Upon the succession of the Protestant Queen Elizabeth I (1558–1603), John was restored to royal favour. He was knighted on 25 December 1576.
He became notorious for engaging in cattle theft, "evil usage in keeping of a castle" (presumably Pendennis) and as a Justice of the peace for abuses in arranging the quarter sessions. Having been appointed a Commissioner to inquire into piracy, he himself was heavily engaged in that activity and traded with smugglers and pirates who frequented the waters around Arwenack. He was the subject of an official investigation in 1565.
In January 1582, both he and his wife, Mary Wolverston, were suspected of involvement in a notorious act of piracy concerning a Spanish ship which had sheltered from a storm in an anchorage opposite Arwenack. It was said that he and his wife had acted together to overpower or murder the crew and steal the cargo of cloth, before ordering the ship to be disposed of in Ireland.
