AMSTERDAM (AP) — A cold case team that combed through evidence for five years in a bid to unravel one of World War II’s enduring mysteries has reached what it calls the “most likely scenario” of who betrayed Jewish teenage diarist Anne Frank and her family.

Their answer, outlined in a new book called “The Betrayal of Anne Frank A Cold Case Investigation,” by Canadian academic and author Rosemary Sullivan, is that it could have been a prominent Jewish notary called Arnold van den Bergh, who disclosed the secret annex hiding place of the Frank family to German occupiers to save his own family from deportation and murder in Nazi concentration camps.

“We have investigated over 30 suspects in 20 different scenarios, leaving one scenario we like to refer to as the most likely scenario,” said film maker Thijs Bayens, who had the idea to put together the cold case team, that was led by retired FBI agent Vincent Pankoke, to forensically examine the evidence.

The Anne Frank House museum in the canal-side Amsterdam building that includes the secret annex welcomed the new research, but said it also leaves questions unanswered.