Editing Henri Désiré Landru (section)

=== Pursuit and arrest ===
The key to Landru's downfall was the persistence of the victims' families, particularly Marie Lacoste (sister of Célestine Buisson) and Victorine Pellat (sister of Anna Collomb). After receiving no reply to letters sent to Buisson at Gambais regarding her blinded son, Lacoste contacted the mayor of Gambais in January 1919.{{sfn|Rēn|1996|pp=60-62}} The mayor, initially unhelpful, eventually put her in touch with Pellat, who had made similar inquiries about Anna Collomb earlier.{{sfn|Rēn|1996|pp=60-62}}{{sfn|Wiruson|Pittoman|1963|pp=144-145}} The two women compared notes, realized the man described (using aliases like "Frémyet" and "Dupont") was the same person, and filed missing persons reports with the prosecutor for Seine-et-Oise.{{sfn|Shōshin Shobō|1997|pp=2812-2815}}<ref name="LacosteAudition"/>

Their complaints eventually reached Inspector Jules Belin of the Paris ''brigade mobile''. While Belin later took credit,<ref name="Belin report"/> the crucial break came on 11 April 1919. Lacoste's friend, Laure Bonhoure, who had previously seen Landru, recognized him shopping on the Rue de Rivoli with a young woman (Fernande Segret).<ref name="Tomlinson arrest"/>{{sfn|Sairyakkusu|1996|pp=662-664}}{{sfn|Rēn|1996|pp=60-62}} Bonhoure alerted Lacoste, who phoned Belin. The inspector obtained the business card Landru (using the alias "Lucien Guillet") had left at the shop, revealing his address: 76 Rue de Rochechouart, near Gare du Nord.{{sfn|Monesutie|1991|pp=100-101}}<ref name="Belin report"/>

After obtaining the correct warrant, Belin and two officers arrested Landru at his apartment around midday on 12 April 1919.{{sfn|Shōshin Shobō|1997|pp=2830-2835}}<ref name="DeslogeresReport"/> As he was led away, Landru reportedly sang an aria from Massenet's opera ''[[Manon (opera)|Manon]]'' to Fernande Segret.{{sfn|Sairyakkusu|1996|pp=662-664}}