Debyes son, Peter P. Debye, interviewed in 2006 at age 89 recollects that his father was completely apolitical and that in the privacy of their home politics were never discussed. According to his son, Debye just wanted to do his job at the Kaiser Wilhelm Institute and as long as the Nazis did not bother him was able to do so. He recalls that his mother urged him (the son) to stay in the US in the event of war. Debyes son had come to the US on a planned 2-month vacation during the summer of 1939 and never returned to Germany because war broke out.
In an opinion article published on the Debye Institute website, Dr. Gijs van Ginkel, until April 2007 Senior Managing Director of the VM Debye Instituut in Utrecht deplored . In his article he cites scholars who point out that the DPG was able to retain their threatened staff as long as could be expected under increasing pressure from the Nazis. He also puts forward the important argument that when Debye in 1950 received the Max Planck medal of the DPG, nobody objected, not even the known opponent of the national socialists Max von Laue, who would have been in a position to object. Also Einstein, with his enormous prestige, was still alive, as were other Jewish scientists such as Lise Meitner and James Franck who both knew Debye intimately. None of them protested against Debye's receiving the highest German scientific distinction. In fact, Albert Einstein, after many years of not participating in the voting for the Max Planck Medal nominees, joined the process again to vote for Debye.
Maastricht University also announced that it was reconsidering its position on the Peter Debye Prijs voor natuurwetenschappelijk onderzoek (Peter Debye Prize for scientific research).
In a reply on the DPG website, Dieter Hoffmann and Mark Walker also conclude that Debye was not a Nazi activist. They remark that Max von Laue also was required and obliged (as a civil servant) to sign letters with Heil Hitler. They also state that the DPG was one of the last scientific societies to purge the Jewish members and only very reluctantly. They quote the response of the Reich University Teachers League (a National Socialist organization) to the Debye letter:
Obviously the German Physical Society is still very backward and still clings tightly to their dear Jews. It is in fact remarkable that only "because of circumstances beyond our control" the membership of Jews can no longer be maintained
In May 2006, the Dutch Nobel Prize winner Martinus Veltman who had written the foreword to the Rispen book, renounced the book's description of Peter Debye, withdrew his foreword, and asked the Board of Directors of Utrecht University to rescind their decision to rename the Debye Institute.
Various historical investigations, both in The Netherlands and in the US, have been carried out subsequent to the actions of the University of Maastricht. The earliest of these investigations, carried out by the Cornell University's department of Chemistry and Chemical Biology released a report on 31 May 2006, which states that:
Based on the information to-date, we have not found evidence supporting the accusations that Debye was a Nazi sympathizer or collaborator or that he held anti-Semitic views. It is important that this be stated clearly since these are the most serious allegations.
It goes on to declare:
Thus, based on the information, evidence and historical record known to date, we believe that any action that dissociates Debyes name from the Department of Chemistry and Chemical Biology at Cornell is unwarranted.'
In June 2006, it was reported that the scientific director of the (formerly) Debye Institute had been reprimanded by the board of directors of the University of Utrecht for a new publication on Debyes war years on the grounds that it was too personally biased with respect to the Institutes naming dispute. According to the board, the book should have been published not as a Debye Institute publication, but as a personal one. The book was banned by the University of Utrecht and both Directors of the (former) Debye Institute were forbidden to have any further contact with the press. A dozen professors of the Physics Faculty, amongst whom Cees Andriesse, openly protested against the interventions of the Board and the censorship of their protest by the university.
In May 2007, the universities of Utrecht and Maastricht announced that a new committee headed by Jan Terlouw would advise them regarding the name change. Also, in the beginning of 2007 an official report was announced, to be published by the NIOD and authorized by the Dutch Education Ministry (then scheduled for  fall 2007).