Love from Felicie

Why was Jules Lapie, known as Jambe-de-Bois, murdered in his home, who was spending a peaceful old age in his new home near Poissy? Maigret felt that Félicie, Lapie's maid, who had gone out to shop at the time of the assassination, knew something, but she remained silent; her behaviour irritated and intrigued the Commissioner, who hardly left her during her investigation.