On March 31st, Madeleine gave a lengthy statement to the Sheriff-Substitute of Lanarkshire stating that she had last seen Emile three weeks previous to his death. She did not deny that they had been lovers, that she had written the letters to him, or that they had seriously discussed marriage. Neither did she deny making three purchases of arsenic in the previous month. She had mixed the arsenic with water and washed her arms and face with it, a cosmetic use she had learned while at school. She had lied to the apothecary about the arsenic's use, she said, because she was too self-conscious to say that it was for her complexion. She said that she "never administered, or caused to be administered, to M. L'Angelier arsenic or anything injurious -- and this I declare to be truth."

Because of the immense and sudden popular interest in the case, the trial was moved from Glasgow to Edinburgh and began June 30, 1857. Madeleine was represented by a team including one of the greatest legal minds of the time, John Inglis. Due to the court rules of the time Madeleine was not allowed to take the stand in her own defense, but had to rely solely on her legal counsel and on her deposition. During the trial, people swarmed the courthouse to catch a glimpse of Madeleine, and crowds lined the streets every night as her carriage took her back to the East Jail of Edinburgh. The newspapers carried detailed descriptions of every aspect of the trial, and the proceedings became the chief topic of conversation throughout Scotland.

The Prosecution argued for the court to admit all of Madeleine's letters and all of Emile's papers as evidence. Inglis argued that her letters could be presented, but that a diary found in his room should not be admitted into evidence. The Prosecution stated that the diary should be admitted, as it contained notations that indicated that Emile had seen Madeleine right before his first and second attacks of the stomach illness. But with the author of the diary now dead, Inglis maintained, the written entries could not be questioned or properly cross-examined. The reasons were persuasive on both sides, but Inglis won and the diary was withheld from the jury.

The trial went on for nine days and many witnesses, including Madeleine's sister Janet (who shared a room with Madeleine and testified that she did not recall Madeleine ever getting out of bed the night of March 22nd) and William Minnoch (who had quickly withdrawn his marriage proposal) took the stand. The Prosecution called witnesses to testify about the contradictions in Madeleine's story -- but the Defense countered with experts who discussed arsenic's cosmetic uses and called witnesses who claimed Emile had made statements to them regarding several prior suicide attempts.

Madeleine showed remarkable calmness and poise during the trial, refusing food and water while in court, but keeping a small vial of smelling salts, which she never had to use. She followed the questioning of witnesses closely and only showed discomfort when the text of some of her letters to Emile were read aloud.

The Prosecution argued that Madeleine had already lied at least once about the real purpose of the arsenic -- to the apothecary -- and stated that Emile's refusal to return her letters and end the affair was motive enough for killing him. Inglis countered by saying that nobody could solidly disprove Madeleine's claim that she had not seen Emile in the three weeks before his death. And, Inglis pointed out, Emile had his first attack two days before Madeleine's first recorded purchase of arsenic.

The Prosecution and the Defense both argued brilliantly, but due primarily to the fact that it could not be shown that Madeleine and Emile had actually seen each other before any of his three attacks, the jury deliberated for only 30 minutes on July 9th and then reached a verdict of "not proven" for the murder charge, and Madeleine went free that afternoon and returned to the Smith home.

The notoriety of the trial eventually necessitated Madeleine's leaving of Scotland, however.

She went to London and eventually married George Wardle, a draftsman, in July of 1861. She continued to remain silent about the trial and her accused crime, although newspapers and curiosity-seekers hounded her. After many years of marriage and two children, Madeleine and George separated.

Madeleine's trail after her separation from George gets fuzzy, and wild rumors of her living (or dying) in places such as Australia and France appeared from time to time in various newspapers. A common theory, that she died under a different name in New York City in 1928, is contradicted by documentation regarding that particular New York City woman.

Wherever and whenever Madeleine passed away, she took whatever she knew about Emile's death with her to her grave.