French housemaid whose research helped lead to the arrest of serial killer Henri Désiré Landru (1869-1922) who murdered at least seven women in the village of Gambais between December 1915 and January 1919, including her older half-sister Célestine Buisson.
The unmarried Lacoste disliked Landru, alias George Frémyet, from the moment she first met him at Buisson’s apartment in the summer of 1915. Over the next two years, Lacoste began to suspect that Buisson’s fiancé was a marriage swindler, out to get his hands on the naive Buisson’s savings. Lacoste’s suspicion was confirmed during a visit with Buisson to the Villa Tric in August 1917, when Buisson admitted that “Frémyet” had taken charge of her investments. Buisson refused to take Lacoste’s advice to end her engagement to “Frémyet” and the two siblings were scarcely on speaking terms when they returned to Paris. A day later, Landru took Buisson back to Gambais, travelling on a one-way train ticket. She was never seen again. Landru murdered her in September that year.
During the autumn of 1917, Landru became increasingly worried that Lacoste might suspect him of Buisson’s murder. He tried to reassure Lacoste that her half-sister was still alive by sending her two fake postcards from Gambais, purportedly signed by “Célestine”. Lacoste instantly realized the signatures were forgeries, but having concluded that Landru was just a con man, did not take any other action. Still worried, Landru turned up alone on several occasions at Lacoste’s workplace to invite her to dinner with Buisson at Buisson’s apartment in Paris. Landru knew the apartment was empty and almost certainly intended to kill Lacoste there. Each time, Lacoste refused, eventually telling Landru to get lost and not to come back.
For the next year, Lacoste mentally washed her hands of Buisson, deciding that her half-sister was too ashamed about falling into the clutches of a crook to want any further contact between them. Then in December 1918 Lacoste received a letter which stirred her into action. Buisson’s son had been blinded during the war and from his home in southwest France, had tried to contact Buisson to borrow money, following what he called a “serious accident”. She had not replied, prompting the son to ask Lacoste if she could intervene with Buisson on his behalf. Lacoste visited Buisson’s old apartment, where the concierge told her that Buisson had last been seen there in the summer of 1917 and that at least one other woman had subsequently spent the night at the address with “Frémyet” before he paid off the lease. Thoroughly alarmed, Lacoste concluded that Landru had probably killed Buisson and had been planning to kill her when he invited her to the apartment.
She rapidly compiled a dossier for the police, noting Landru’s physical appearance, his known movements with Buisson since 1915, the location and design of his house near Gambais, his thefts from Buisson’s bank accounts, the forged postcards after her disappearance and his phony invitations to dinner. On 11 January 1919, Lacoste took her dossier to her local police station in Paris, accompanied by a fellow maid called Laure Bonhoure who had seen Landru when he had visited the house where they worked. At the station, a police officer told Lacoste that she needed to contact the authorities in Gambais, where Buisson had vanished. The next day, Lacoste wrote to the mayor of Gambais in her best formal French, forgetting her full stops as she raced on:
“You have in your commune a house at about 100 metres from the church, which is called the Maison Tric, the name of the owner, I do not know him, but the house was rented in 1917, to a gentleman around 40 years old, who had a long brown beard and who has as his name Monsieur Frémyet. Therefore this gentleman lived in this house for a good part of the summer of 1917 with a woman of about 45 to 50, or more exactly 47, with blue eyes and chestnut hair, medium height.”
The mayor denied any knowledge of Célestine Buisson or a man called Frémyet living at the Maison (or Villa) Tric. This claim was well short of the truth, because the mayor recognized the man described accurately by Lacoste by another of Landru’s aliases: “Raoul Dupont”. The mayor did, however, put Lacoste in touch with Victorine Pellat, the younger sister of Landru’s sixth known victim Anna Collomb, who had made an identical inquiry about Collomb in 1917.
Lacoste contacted Pellat and after conferring about their separate investigations, they filed two missing person complaints with the prosecutor’s office in the department of Seine-et-Oise, where Gambais was located. By a desultory route, the cases finally wound their way back to Inspector Jules Belin of the Paris flying squad (brigade mobile).
Belin interviewed Pellat and Lacoste and then plagiarized most of the latter’s research for an internal police report in which he falsely took the credit for Landru’s arrest. In reality, Landru’s capture was entirely due to a chance sighting of him on 11 April 1919 by Lacoste’s friend Laure Bonhoure as he was shopping with his mistress Fernande Segret in a crockery shop on Rue de Rivoli. Bonhoure tried to follow Landru after he left the shop, but fearing he had recognized her, she ran home to tell Lacoste, who phoned Belin with the news. Belin retrieved the business card that Landru, alias “Lucien Guillet”, had given to a shop assistant and visited the address indicated: 76 Rue de Rochechouart, near the Gare du Nord. However, Belin only had an arrest warrant for a man called “Frémyet”, so decided to go home for the night.
On 12 April, at around 11 AM, Belin returned with two fellow officers and a newly-drafted warrant and arrested Landru, who had just returned from accosting a woman on the metro.
Landru was eventually brought to trial in Versailles in November 1921, after exhausting his appeals against previous convictions. He was found guilty and executed by guillotine just before dawn on 25 February 1922 outside the gates of the Prison Saint-Pierre in Versailles.
Marie Lacoste died on 26 August 1964 at age 78 in Bayonne.
Link to Wikipedia biography