"Was it, in other words, a government-sponsored false-flag operation? Since 2001 the answer has been, almost certainly, yes.
In 1990, 50,000 pages of German court, government and Gestapo files – located both in East Germany and Moscow, became available to a team of researchers, principally the historian Alexander Bahar and physicist and psychologist Wilfreid Kugel who spent a decade carefully reviewing the material before publishing The Reichstag Fire – How History is Created, in 2001.
"On February 27, 1933, at about 8:00 p.m. a commando group of at least 3, and at most 10 SA men [Brownshirts] led by Hans Georg Gewehr entered the basement of the palace of the Reichstag President. The group took the incendiary substances deposited there, and used the subterranean passageway to go from the Reichstag President’s palace to the Reichstag building, where they prepared the assembly hall in particular with a self-igniting liquid they probably mixed in the hall. After a certain latency period, the liquid set off the fire in the assembly hall. The group made their getaway through the subterranean passageway and the basement of the Reichstag President’s palace (and possibly also through the adjacent basement leading to the machinery and government employees’ building) to the public street ‘Reichstagsufer.’ [Reich President Hermann] Göring entered the burning Reichstag building at 9:21 p.m. at the latest, presumably in order to provide a cover for the commando group’s retreat. Van der Lubbe was brought to the Reichstag by the SA at exactly 9:00 p.m. and let into the building by them. The sound of breaking glass which was noticed by witnesses and which was allegedly due to van der Lubbe breaking window panes to get into the building was probably only intended to attract the attention of the public."
Just three hours before the Reichstag fire, the head of the political police (and subsequently of the notorious Gestapo), Rudolf Diels, had sent a telegram to all police stations in Prussia warning them of a plan by communists to raid police stations and “nationalist associations” (a euphemism for Nazi Party armed squads) and disarm them. The police were to take “suitable countermeasures” and arrest communist functionaries.
There was, of course, no such communist plot, but thousands were arrested and all left-wing newspapers were closed down. Two days after the fire, two decrees annulled the essential basic rights incorporated in the constitution of the Weimar Republic. They stayed in effect until the collapse of the Third Reich and formed the pseudo-legal basis for the Nazi dictatorship."