Several addresses for Landru are given:
Ateliers du Progrés Automobile, 58 Bld St Germarin, Paris (1900)
6 rue des Carrières Montmorency
15 Bld Pereire Paris
The first machines were motorcycles which could be converted to tricycles, and then in 1900 he developed a machine with a 198cc Renouard engine. An example of this was included in the auction of the Guélon Collection
Landru's assets were transferred to Labitte in April 1900.
Landru proposed many designs, and in a large advertising campaign offered to build motorcycles for buyers who would make a deposit of one third of the price. It seems that few of the customers ever saw their finished machines, nor their money again.
Wikipedia states that he "then deceived several potential investors into giving him money to build a factory to manufacture it. Having pocketed the money, Landru vanished."
He engineered a long list of scams, and in 1904 he was sentenced to two years jail for fraud. Some years later he served 3 years, again for fraud.
In 1913/1914 he again defrauded a number of investors in an automobile factory he was to have built. He vanished again, this time with the substantial inheritance he had stolen from his wife and children, left to them by her father who had hung himself in despair of her husband's actions.
Landru was neither the first nor the last motorcyclist to lose his head but in France he is the most famous. Unlike Enoch Thulin whose head was detached and bounced along like a football, Landru's simply plopped into a bucket. He had been convicted as a serial killer and executed by guillotine.
Landru was arrested on 12 April 1919 at an apartment near Gare du Nord in Paris which he shared with his 24-year-old mistress, Fernande Segret. The police eventually concluded that Landru had met or been in romantic correspondence with 283 women during the First World War, including 72 who were never traced.
"...the true number of Landru's victims, whose remains were never found, was almost certainly higher."
Sources: Bourdache (pp 102, 103, 109.), en.wikipedia.org, et al.