Horst Tappert, who played the beloved baggy-eyed detective from 1974 to 1998 in a programme that ran in more than 100 countries, was a member of an SS tank regiment on the Russian front, according to the report.
Military archives showed Tappert joined the Waffen SS at the latest in 1943 when he was 20, the newspaper said. Tappert died in 2008. Several prominent Germans kept quiet after the war about their service in the Waffen SS, an elite corps responsible for some of the Nazis' worst atrocities.
"In his memoirs as well as in all his public remarks on the war years, Tappert never made mention of this," the newspaper said.
"In an interview he said he was a medic and was taken prisoner at the end of the war."
The report was based on the findings of sociologist Jörg Becker, who, while working on a biography of another academic, Elisabeth Noelle-Neumann, looked into the personal histories of members of a theatre company she
Tappert belonged to the troupe in 1947. When Becker examined the archives of the notification service for next-of-kin of Wehrmacht soldiers killed in action (WASt), the researcher found the actor's name.
The Berlin-based WASt, which also has vast files on soldiers who survived the war, said Tappert started as a reservist in an anti-aircraft battery before joining the Totenkopf (Death's Head) tank regiment.
Military expert Jan Erik Schulte said it was unclear under what circumstances Tappert joined the corps.
"The pressure particularly on young men to become Waffen SS members in 1943 was indeed enormous," after the disastrous battle of Stalingrad, he told news website Spiegel Online.
He noted that according to the files, Tappert held the lowest rank in the SS and although the corps as a whole had committed mass killings in the Soviet
Union, it was not clear whether Tappert had been personally involved.
Association with the SS has come back to haunt other high-profile Germans. A Nobel literature laureate, Gunter Grass, saw his substantial moral authority undermined by his admission in 2006, six decades after World War II, that he had been a member of the Waffen SS as a 17-year-old.