Notorious guests at the Neuilly house

The Der Spiegel article lists several names among the guests of Walter and Laure Kleinknecht at the Neuilly villa. The two French names, Pierre Laval and Marcel Déat, were leading politicians in the Vichy government. From Wikipedia:

Pierre Laval

Pierre Laval (French pronunciation: [pjɛʁ laval]; 28 June 1883 – 15 October 1945) was a French politician. He was four times President of the council of ministers of the Third Republic, twice consecutively.

Following France's surrender and Armistice with Germany in 1940, he served twice in the Vichy Regime as head of government. He signed orders permitting the deportation of foreign Jews from French soil to the Nazi death camps.

After Liberation (1945), Laval was arrested by the French government under General Charles de Gaulle, found guilty of high treason, andexecuted by firing squad. The controversy surrounding his political activities has generated a dozen biographies.

Marcel Deat

Marcel Déat (7 March 1894, Guérigny, France – 5 January 1955, near Turin, Italy) was a French Socialist until 1933, when he initiated a spin-off from the French Section of the Workers' International (SFIO) along with other right-wing 'Neosocialists'. He then founded the collaborationist National Popular Rally (RNP) during the Vichy regime. In 1944, he became "Minister of Labor and National Solidarity" in Pierre Laval's government, before escaping to Sigmaringen along with Vichy officials after the Allied landings in Normandy. Condemned in absentia for collaborationism, he died while still in hiding in Italy. 

There is no Wikipedia entry for the German name mentioned, Colonel Engelke, but I have found some other interesting information, described in the following post.