Fingerprinting in 1900
In 1684, Dr. Nehemiah Grew wrote a Royal Society of London paper containing accurate drawings of finger ridge patterns, although it wasn't for another two hundred years that these idiocyncrasies of the human body were used for personal identification.
In 1858, when Sir William James Herschel, Chief Magistrate in Jungipoor, India, had a local businessman, impress his handprint on a contract, allegedly to discourage him from repudiating his signature. This worked so well, Herschel made a habit of requiring palm prints, then later the prints of the right index and middle fingers. This led to the local superstition that personal contact with the document made the contract more binding than just signing it. Over time, Herschel learned that the inked impressions could prove or disprove identity.
Dr. Henry Faulds used printers ink to obtain fingerprints, and was credited with the first fingerprint identification of a greasy fingerprint left on an alcohol bottle. He passed his findings to Sir Charles Darwin in 1880, however Darwin was in poor health at the time and passed the information to his cousin, Francis Galton.
Sir Francis Galton, a British anthropologist, took up this use of fingerprints as a means of identification in 1888, publishing three books on the subject between 1892 and 1895. His main aim was to use fingerprints to determine heredity and racial background, but he soon confirmed what Herschel and Faulds already suspected: that fingerprints do not change over the course of an individual's lifetime, and that no two fingerprints are exactly the same. He calculated that the odds of two individual fingerprints being the same were 1 in 64 billion and some characteristics still in use today are sometimes referred to as Galton Details.
In 1901, a Fingerprint Branch was established at Scotland Yard by the Metropolitan Police.
In July 1902, a burglary occurred in a house in Denmark Hill, London, and some billiard balls were stolen. An impression of a left thumbprint on a windowsill led to the conviction of a Harry Jackson - the first criminal trial in the UK where an individual was convicted based on fingerprint evidence.
Although Flora Maguire in Murder on the Minneapolis might be aware that fingerprinting was being studied, she also knew that no one had yet been convicted in a British court by a fingerprint - thus she and her detective friend will have to catch the killer another way.