An extraordinary untold chapter of cold-war espionage has emerged with the revelation that secret services in the Eastern Bloc systematically stole the identities of orphaned and abandoned children and used them to create aliases for their foreign agents.
The details have come to light in a German documentary that tells the tragic story of a Polish man whose identity was assumed by a spy for the Polish secret service who infiltrated West Germany's civil service and remained active there for years.
Jerzy Kaczmarek was recruited as an agent in 1977 when he was in his early 20s, and given the identity of Janusz Arnoldt.
Arnoldt had been born in 1946 to an ethnic-German mother who abandoned the one-year-old in an orphanage after fleeing her home in Pomerania - which later became Polish - along with hundreds of thousands of other ethnic Germans.
To perfect his cover and enable him to operate in Germany, the spy Kaczmarek made an application through the Red Cross to track down "his" (Arnoldt's) birth mother, who lived in West Germany. The family welcomed the long-lost "son" with open arms, but were stricken with grief when Arnoldt's "mother", Hildegard, dropped down dead at her front door hours after seeing her supposed son in West Germany for the first time.
Helped by his new family, who took him to their hearts, Jerzy Kaczmarek went on to make a successful career for himself posing as a German bureaucrat in the northern city of Bremen's office of emigration and immigration, where he was a popular colleague, admired for the speed with which he mastered bureaucratic German. He even became a respected member of the Social Democratic Party.
By day he pushed papers and oversaw the applications of ethnic Germans wishing to return to Germany; by night, he sent vital information back to his spymasters, who gave him orders via a short-wave radio at his flat.
Slavomir Cenckiewicz, a historian who oversaw the shutting down of the Polish military secret service in the 1990s, said the work Kaczmarek carried out was hugely valuable for the entire Eastern Bloc secret-service network.
"Having a mole planted in the system was like gold dust. He was able to help with the infiltration of spies into the West, as well as observing how German authorities controlled those wishing to flee communism," he said.
But Kaczmarek's cover was blown when the real Janusz Arnoldt applied via the German Red Cross in the mid-1980s to track down his birth mother, only to be told that the request had been lodged from Eastern Europe years before and that a reunion had long since taken place.
The inquiry prompted the West German authorities to confront the man posing as Arnoldt and to arrest him. After 10 months in custody and an extensive investigation by West Germany's federal public prosecutor, who discovered at his home his short-wave radio, a photographic laboratory, a briefcase with false compartments and the nutcracker in which he stored secret access codes, Kaczmarek was expelled in 1986.
But a heart-wrenching twist to the tale, and one which the family of the real Janusz Arnoldt has urged the Polish authorities to investigate, was Arnoldt's sudden death at the age of 38 in June 1985, three days after he had discovered that his identity had been stolen by a spy and that his mother was dead. An official protocol stated he had "probably died of a heart attack", but no autopsy was carried out.
The story has come to light thanks to the dogged investigative efforts of a Polish author, Rosalia Romaniec.
"I was desperate to get to the heart of a story that has haunted me and my family for over three decades," she said. Janusz Arnoldt was her uncle.
Romaniec, who tracked down Kaczmarek in Poznan, Poland, said that while her investigation had brought the family some answers, it had left her feeling very uneasy about the "unknown legacy of the cold war".
"How many cases similar to this are there still in the East and the West?" she asked. "How many people are living with assumed identities, living the life of someone else?"