'"All the tests that we have done over the past five years -- on the materials and other aspects -- do not show any signs of forgery," said Rene Larsen, rector

'"All the tests that we have done over the past five years -- on the materials and other aspects -- do not show any signs of forgery," said Rene Larsen, rector of the School of Conservation under the Royal Danish Academy of Fine Arts, during an interview with Reuters.' So they failed to refute the null hypothesis. In science, we call this "failure to find", NOT confirmation of the null hypothesis.