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
Assets transferred to Labitte in April 1900 (1)
Several addresses are given:
58 Bld St Germarin, Paris (Sales, probably), 6 rue des Carrières Montmorency, and 15 Bld Pereire Paris.
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.
Notes. 1) This was possibly because he was sentenced to two years jail in 1900 for fraud.
Sources: Bourdache (pp 102, 103, 109.) and others.