Spy in the context of "Pieter Isaacsz"

Treason is the crime of attacking a state authority to which one owes allegiance. This typically includes acts such as participating in a war against one's native country, attempting to overthrow its government, spying on its military, its diplomats, its officials, or its secret services for a hostile foreign power, or attempting to kill its head of state. A person who commits treason is known in law as a traitor.

Historically, in common law countries, treason also covered the murder of specific social superiors, such as the murder of a husband by his wife or that of a master by his servant. Treason (i.e., disloyalty) against one's monarch was known as high treason and treason against a lesser superior was petty treason. As jurisdictions around the world abolished petty treason, "treason" came to refer to what was historically known as high treason.

John Dee (13 July 1527 – December 1608 or March 1609) was an English mathematician, astronomer, teacher, astrologer, occultist, and alchemist. He was the court astronomer for, and advisor to, Elizabeth I, and spent much of his time on alchemy, divination, and Hermetic philosophy. As an antiquarian, he had one of the largest libraries in England at the time. As a political advisor, he advocated the foundation of English colonies in the New World to form a "British Empire", a term he is credited with coining.

Dee eventually left Elizabeth's service and went on a quest for knowledge of the occult and supernatural. He aligned himself with several individuals who may have been charlatans, travelled through Europe, and was accused of spying for the English Crown. Upon his return to England, he found his home and library vandalised. He eventually returned to the Queen's service, but was turned away when she was succeeded by James I. He died in poverty in London, and his gravesite is unknown.

In the field of counterintelligence, a double agent is an employee of a secret intelligence service for one country whose official purpose is to spy on a target organization of another country, but who is now spying on their own country's organization for the target organization.

Double agentry may be practiced by spies of the target organization who infiltrate the primary, controlling organization or may result from the turning (switching sides) of previously loyal agents of the controlling organization by the target. The threat of execution is the most common method of turning a captured agent (working for an intelligence service) into a double agent (working for a foreign intelligence service) or a double agent into a re-doubled agent. The double agent is unlike a defector, who is not considered an agent, as agents are posted to function for an intelligence service and defectors are not, although some consider that defectors have been agents de facto until they have defected.

In espionage jargon, a mole (also called a "penetration agent", "deep cover agent", "illegal" or "sleeper agent") is a long-term spy (espionage agent) who is recruited before having access to secret intelligence, subsequently managing to get into the target organization. However, it is popularly used to mean any long-term clandestine spy or informant within an organization (government or private). In police work, a mole is an undercover law-enforcement agent who joins an organization in order to collect incriminating evidence about its operations and to eventually charge its members.

The term was introduced to the public by British spy novelist John le Carré in his 1974 novel Tinker Tailor Soldier Spy and has since entered general usage, but its origin is unclear, as well as to what extent it was used by intelligence services before it became popularized. Le Carré, a former British intelligence officer, said that the term "mole" was actually used by the Soviet intelligence agency, the KGB, and that a corresponding term used by Western intelligence services was sleeper agent. While the term mole had been applied to spies in the book Historie of the Reign of King Henry VII written in 1626 by Sir Francis Bacon, Le Carré said he did not get the term from that source.

A prisoner exchange or prisoner swap is a deal between opposing sides in a conflict to release prisoners: prisoners of war, spies, hostages, etc. Sometimes, dead bodies are involved in an exchange.

Clandestine human intelligence is intelligence collected from human sources (HUMINT) using clandestine espionage methods. These sources consist of people working in a variety of roles within the intelligence community. Examples include the quintessential spy (known by professionals as an asset or agent), who collects intelligence; couriers and related personnel, who handle an intelligence organization's (ideally) secure communications; and support personnel, such as access agents, who may arrange the contact between the potential spy and the case officer who recruits them. The recruiter and supervising agent may not necessarily be the same individual. Large espionage networks may be composed of multiple levels of spies, support personnel, and supervisors. Espionage networks are typically organized as a cell system, in which each clandestine operator knows only the people in his own cell, perhaps the external case officer, and an emergency method (which may not necessarily involve another person) to contact higher levels if the case officer or cell leader is captured, but has no knowledge of people in other cells. This cellular organization is a form of compartmentalisation, which is an important tactic for controlling access to information, used in order to diminish the risk of discovery of the network or the release of sensitive information.