Shortly after 3:30 a.m., Charles Cross walked through the teeming slums of London’s Whitechapel neighborhood on his way to work. As he walked down Buck’s Row—a quiet byway flanked by warehouses and shabby, two-story cottages—Cross peered through the darkness and spotted something unusual slumped against the gated stable entrance on the other side of the street. As Cross inched closer over the cobblestones, he made a grisly discovery. “I could not tell in the dark what it was at first,” he said. “It looked to me like a tarpaulin sheet, but stepping into the road, I saw it was the body of a woman.”

The victim’s skirt had been raised almost to her stomach, and blood had puddled from a wound across her throat. The post-mortem examination detailed the gruesome slaying. The murderer had slit her throat twice from left to right, leaving a four-inch and an eight-inch gash. The mutilated victim had sustained jagged wounds to her abdomen.

“The wounds must have been inflicted with a strong-bladed knife, moderately sharp, and used with great violence,” reported the medical examiner, who estimated that the victim had been dead for about a half-hour by the time Cross discovered her body. Although bruises blemished the face and neck of the victim and a ring was missing from her finger, there had been no sign of a struggle at the crime scene and the Buck’s Row residents had heard no screams during the night.

The authorities identified the victim as 43-year-old Mary Ann Nichols, one of the hundreds of prostitutes who prowled the warren of Whitechapel’s streets. Nicknamed “Polly,” the downtrodden Nichols drank so heavily that it shattered her marriage, cost her the custody of her five children and left her destitute. She moved from workhouse to workhouse in the run-down East End and even slept nights in Trafalgar Square. When Nichols had finally found respectable work as a servant, she lost the job after stealing clothes from her employer.

A friend, Emily Holland, had spotted Nichols outside a grocer’s shop opposite Whitechapel Church around 2:30 a.m. on the morning of August 31. As the inebriated Nichols leaned against the wall for balance, Holland urged her to come with her to a nearby lodging house. Nichols refused and staggered into the night. An hour later, her body was discovered. She was wearing workhouse-issued clothing and bearing all her worldly possessions—a white handkerchief, a comb and a bit of broken looking glass.

The savagery of the crime shocked Victorian sensibilities. “The brutality of the murder is beyond conception and beyond description,” reported The Star. Just two days after Nichols was buried, London arose on September 8 to find that the mutilated body of another Whitechapel prostitute, Annie Chapman, had been discovered just blocks away from the location of Buck’s Row. The details of the vicious murder mirrored those in the stabbing of Nichols, and the manhunt began for a serial killer.

A media frenzy erupted. A letter sent to the authorities that contained facts that would only have been known to the police and the killer was signed, “Jack the Ripper.” The “Autumn of Terror” consumed London as two more prostitutes—Elizabeth Stride and Catherine Eddowes—were found butchered on September 30. The slaughtered body of the fifth and final victim, Mary Kelly, was discovered on November 9. Despite the incredible attention devoted to the case, all trails to the identity of Jack the Ripper reached a dead end.

Even over 125 years later, Jack the Ripper remains one of history’s most infamous serial killers and a subject of intense fascination that has spawned books, movies and even popular walking tours of the crime scenes. Generations of “Ripperologists” have speculated that Nichols may not have been the first of Jack the Ripper’s victims and that the killer could have been responsible for as many as 11 unsolved murders in Whitechapel.

Countless theories have been floated about the true identity of the killer, and fingers have even been pointed at famous figures including “Alice’s Adventures in Wonderland” author Lewis Carroll, the father of Winston Churchill, and a member of the royal family, Queen Victoria’s eldest grandson and heir to the throne, the Duke of Clarence. Officially, however, authorities closed the Jack the Ripper file in 1892, and the five Whitechapel murders remain among the most notable cold cases in history.