Thomas W. Piper was born on April 22, 1849, in Yarmouth, Nova Scotia, the second-born son of T. C. Piper, a local farmer. In 1866, he moved to Boston with his family, harboring ambitions beyond farm life. He took on clerk positions around the city, and due to his solid reputation as a literate, church-going young man, earned a trusted spot as the sexton for the Warren Avenue Baptist Church. Yet beneath his respectable front lurked a troubled side: Piper suffered from a kidney disorder and self-medicated with a cocktail of laudanum mixed with alcohol—hallucinogenically potent and addictive. Unbeknownst to his congregation and neighbors, he began dabbling in arson. 

On the night of December 5, 1873, while walking to church with his brothers in Dorchester, Piper abruptly claimed to feel ill and detoured to buy opium, mixing it with alcohol before returning home. In a delirious haze, he sawed a section of a wooden shaft and concealed it under a fence. At some point, a fire alarm drew Piper back to the street where he noticed Bridget Landregan, a well-regarded domestic servant walking home. Piper slipped away from his brothers, retrieved the hidden shaft, and followed her into the gloom of Columbia Street. Suddenly, she turned, and he struck her with the shaft—twice—crushing her skull and killing her instantly. Nearby footsteps made Piper flee, thrusting a knife into fleeing shadows, and taking a convoluted route home to obscure his trail. Several men, including Piper, were arrested but released for lack of evidence.

Sometime in 1874, Piper noticed Mary Tyner, a prostitute, in downtown Boston. They had drinks, fell asleep at her place, and in the middle of the night, he used a hammer-like object to strike her multiple times in the head. Tyner survived but suffered permanent incapacitation and was committed to a lunatic asylum; she could not identify her assailant. Piper again evaded justice, as insufficient evidence prevented his arrest.

On May 23, 1875, during a Sunday service at the church where he worked, Piper led five-year-old Mabel Hood Young up to the belfry under the pretense of showing her pigeons. Once alone, he bludgeoned her with a cricket bat, intending to kill and perhaps sexually assault her. Mistakenly believing she was dead, he moved her from the scene and escaped. She was discovered later, mortally injured, and died the following evening. A witness recalled seeing him leap from the belfry in panic.

Piper’s first trial ended in a hung jury, nine jurors voted guilty, three acquitted—under tremendous media and public pressure. However, during his second trial, circumstantial evidence proved enough for a conviction. Throughout the ordeal, Piper had maintained his innocence, even concocting a bizarre account about a trapdoor accident involving Mabel. But ultimately, he confessed not just to the murder of Young but also admitted guilt in the murders of Landregan, the assault on Tyner, and the suspected killing of Minnie Sullivan. He was sentenced to death and executed by hanging on May 26, 1876. An estimated 300 people attended the execution, held at the Suffolk County Jail. Piper was buried privately in Mount Hope Cemetery, and his family requested that his written confession remain sealed; the sheriff agreed.