Jack Unterweger, born on August 16, 1950, in Judenburg, Styria, Austria, had a tumultuous early life. His mother, Theresia Unterweger, was a Viennese barmaid and waitress who had a brief relationship with an American soldier named Jack Becker, whom she met in Trieste, Italy. Some accounts suggest that Theresia was involved in prostitution. While pregnant with Jack, Theresia was imprisoned for fraud. She was released before his birth and moved to Graz, where Jack was born. However, in 1953, she was arrested again, leading to Jack being sent to Carinthia to live with his grandfather. This grandfather was notorious for his rough behavior and often involved Jack in stealing farm animals.

Throughout his youth, Unterweger had numerous run-ins with the law. He briefly worked as a waiter, but between 1966 and 1974, he faced sixteen convictions, primarily for theft. His criminal activities also included pimping and sexually assaulting a sex worker. As a result, he spent the majority of these eight years behind bars.

In 1974, Jack Unterweger murdered 18-year-old Margaret Schäfer, a West German national, by strangling her with her own bra. Convicted in 1976, he received a life sentence. During his incarceration, Unterweger penned various literary works, including short stories, poems, plays, and an autobiography titled "Purgatory or The Trip to Prison – Report of a Guilty Man." This book later inspired a documentary. However, some, including Austrian writer Elfriede Jelinek, have doubted the authorship of "Purgatory."

By 1985, a movement began advocating for Unterweger's pardon and release. Despite the campaign, Austrian President Rudolf Kirchschläger initially rejected the petition, emphasizing the court's minimum requirement of fifteen years in prison. Prominent figures such as Jelinek, German novelist Günter Grass, and Alfred Kolleritsch, editor of the magazine Manuskripte, supported the call for Unterweger's release.

Unterweger was finally released on May 23, 1990, after serving the minimum fifteen years. Post-release, his autobiography was included in Austrian school curriculums, and his children's stories were aired on Austrian radio. Unterweger even hosted television programs on criminal rehabilitation and worked as a journalist for ORF, the public broadcaster, covering stories related to murders for which he would later be found guilty.

Subsequent investigations revealed that Unterweger murdered Blanka Bočková in Czechoslovakia, along with seven other women in Austria in 1990. These victims—Brunhilde Masser, Heidi Hammerer, Elfriede Schrempf, Silvia Zagler, Sabine Moitzl, Karin Eroglu-Sladky, and Regina Prem—were all strangled with their own bras.

In 1991, an Austrian magazine commissioned Unterweger to report on crime in Los Angeles, comparing U.S. and European approaches to prostitution. During his time there, he liaised with local police and even joined a ride-along in the city's red-light districts. During his stay, three sex workers—Shannon Exley, Irene Rodriguez, and Peggy Booth—were murdered in a manner similar to his previous victims.

Back in Austria, Unterweger became a suspect in the sex worker murders. Despite their suspicions, police surveillance found no direct evidence linking him to the crimes. When they finally had enough evidence to arrest him, Unterweger had already fled. A manhunt ensued, and he was eventually apprehended by U.S. Marshals in Miami, Florida, on February 27, 1992, after evading authorities across several countries.

Unterweger was extradited to Austria on May 27, 1992, and charged with eleven murders, including those in Prague and Los Angeles. The jury found him guilty of nine murders by a 6:2 majority, which was sufficient for a conviction under Austrian law. Dr. Reinhard Haller, an Austrian psychiatrist, diagnosed Unterweger with narcissistic personality disorder, presenting his findings to the court on June 20, 1994. On June 29, Unterweger received a life sentence without the possibility of parole.

That same night, Unterweger committed suicide in Graz-Karlau Prison by hanging himself with a rope made from shoelaces and a tracksuit cord, using the same knot found on his victims. Before his death, Unterweger had expressed his intention to appeal his conviction. Consequently, under Austrian law, his guilty verdict was not considered legally binding as it had not been reviewed and confirmed by the court.