He is often cited as the model for John Le Carre's mythical spy master Karla, but to western intelligence experts the exploits of Markus Wolf, East Germany's chief of foreign espionage for the past three decades, are all too real.

The defection last week of one of Bonn's top counterspies, Hans Joachim Tiedge, is only the latest in a series of espionage coups that consistently remind West German authorities of the vulnerability of their free society to the Communist superspook.

Renowned as a clever innovator in a rigid totalitarian system, Wolf has been aided inestimably by Bonn's open-door policy to German refugees and the common language and culture linking two rival states across the East-West divide. At least 3,000 spies are believed to have infiltrated West German institutions, with thousands of other informers and "sleepers" poised to serve East Berlin's needs, according to Interior Ministry officials in Bonn.

Wolf was raised in the Stuttgart area of what is now West Germany by Communist parents who fled to the Soviet Union when the Nazis came to power. There he picked up the nickname "Mischa" and received his education at Moscow University and a training school run by the Comintern, or third Communist International.

When the German Democratic Republic was formed, he joined its diplomatic service and undertook his first two-year assignment in Moscow. Wolf then joined the Ministry for State Security, the formidable intelligence apparatus known as the "sword and shield of Socialism" that was set up under close Soviet supervision.

Known by the dreaded abbreviation Stasi, the ministry was assigned the tasks of suppressing internal dissent, controlling the heavily guarded borders, monitoring foreigners inside the country and carrying out foreign espionage. At the age of 33, thanks to his keen mind and thorough Soviet training, Wolf was placed in charge of foreign intelligence operations.

In that role, Wolf has earned the grudging respect of his opponents in espionage on the western side of the Wall.

"Wolf has a lot of brains, experience and patience," said a western intelligence official. "But most of all, he's got the cards stacked in his favor in dealing with an open society in West Germany in the same language."

In the treacherous realm of espionage, Wolf also has endured a few blows to his prestige. In 1979, Werner Stiller, a lieutenant in East German intelligence and one of Wolf's bright young proteges, defected to the West.

Stiller, then 31, had been active in running agents in Western nuclear centers, among other things. His defection led to the arrest of 17 East German agents and caused 15 others to flee across the border.

Nonetheless, Wolf's reputation has been so enhanced by valuable acquisitions, such as Tiedge, that he remains the obvious choice to become head of the entire Ministry for State Security as soon as the ailing, 78 year-old Erich Mielke steps down. Wolf's methods as a spy master run from the brilliant to the banal. His most clever tactic, according to intelligence sources, is a refinement of forged identity called "seamless penetration."

From the 1,000 to 2,000 West Germans who move to the East every year, Wolf's department confiscates identity papers and turns them over to agents who then enter West Germany through a third country. Sweden, France and Canada are described as favored choices.

The spy simply renews the cancelled registration of the West German who has left the country with West German police once he arrives. He faces no risk of a computer spotting flaws in forged documents, and since the police usually only bother to check the last departure point, he enters with a "clean" western background.

Two of the spy suspects who vanished from Bonn in recent weeks were ascertained to have settled in West Germany in this manner, including Sonja Lueneburg, the private secretary of Economics Minister Martin Bangemann who had assumed the identity of a West Berlin hair dresser before coming to Bonn from Colmar, France, nearly two decades ago.

In addition, Wolf's spies are accomplished practictioners of more mundane techniques such as luring lonely Bonn secretaries to betray classified material in return for pledges of love or marriage. East Berlin's "Romeos" are known to cruise Bonn bars on weekends seeking to seduce secretaries or to approach those enjoying cheap holidays at Black Sea resorts.

East Berlin's spies have also started to cultivate West Germany's 2 million unemployed by scouring "Jobs Wanted" listings in newspapers to recruit people desperate for work. West German students also are drawn into spying for the East through dummy research organizations that offer substantial fees for useful commercial, political or stragetic papers.

Lately, East Germany has worked hard at gathering technology secrets with considerable success. A report by Bonn's Interior Ministry says East Germany devotes perhaps $3 million every year to economic espionage but reaps $170 million in research and development savings.

Many agents are planted among the hordes of East Germans who reject the Communist system and settle in the West after a long wait for exit visas. Last year's massive wave of 40,000 refugees permitted to leave East Germany is attributed, in part, by intelligence specialists to East Berlin's desire to "seed" a new generation of long-term agents who will strive to attain influential positions in politics and industry. One of Wolf's most accomplished "seeds" was Guenter Guillaume, who left East Germany in 1956 and became active in the Social Democratic Party. He gradually worked his way up the ladder and joined Chancellor Willy Brandt's staff as a personal adviser in 1973. Guillaume was exposed as a Communist agent 15 months later, but not before he was able to gain access to a trove of classified matter. He was given a 13-year prison term but released in 1981 in a spy swap.