Bern, Switzerland ? Swiss authorities knowingly contributed to the Holocaust by turning Jewish refugees back to face their Nazi persecutors, a five-year study funded by the Swiss government concluded Friday.

“Large numbers of persons whose lives were in danger were turned away needlessly,” said Jean-Francois Bergier, who led an international panel of historians given first-time access to government and company archives. “Others were welcomed in, yet their human dignity was not always respected.”

The undertaking, which produced 26 volumes and cost about $13 million, confronted neutral Switzerland with unpleasant truths that historians, Jews and others have long known about its World War II balancing act next to Hitler’s Germany.

Many of the hardest-hitting findings already had been released by the panel as they became available during its five years of research, which far exceeded in scope, financing and access anything that had previously been attempted. But the research continued to make progress on such details as the actual number of refugees admitted and rejected.

Myrtha Welti, secretary-general of the panel, said 24 other countries have undertaken similar studies in recent years, but that none of them approached the Swiss project in scope and access.

The historians said “it must … be assumed that Switzerland turned back or deported over 20,000 refugees” during the war, and that a large proportion were Jewish.

Many of those rejected were believed captured by the Nazis and sent to concentration camps, where they died.