Carl Hau was born on 3 February 1881 in Grosslittgen, a small area near Wittlich in southwest Germany, close to the Luxembourg border. His father, Johan Baptist Hau, worked as a bank director. When Carl was just three years old, his mother passed away. After her death, he was raised and educated in the city of Trier.

Hau later went on to study law at the University of Freiburg. While he was a student, he contracted tuberculosis in 1901, a disease that was common in Europe at the time. To recover, he traveled to the island of Corsica in the Mediterranean Sea. There, he rented a room in the beautiful town of Ajaccio. During this time, he met a widow named Josephina Molitor, who had seven children. Two of her daughters, Lina and Olga, were also staying on the island. Hau and the daughters began to spend time together, and they both found him to be very polite.

Eventually, Lina had to return home to Baden Baden in southwest Germany. Hau offered to accompany her back home. He was six years younger than Lina, but he was the same age as Olga. It is believed that Josephina might have hoped for a match between Carl and Olga instead of Lina.

In June 1901, Hau and Lina ran away together to Switzerland. They took 2000 marks from Lina's savings. During the summer, there was an incident in Realp where Lina was shot in the chest, which was said to be part of a suicide pact. After recovering, Josephina allowed them to marry in August 1901 in Mannheim. Following their marriage, the couple moved to the United States and settled in Washington, D.C. There, Hau continued his law studies, graduating with a Bachelor of Arts degree in 1904. He was admitted to the bar in early 1906.

In 1904, Hau secured a position as Secretary to the Turkish Consul in Washington, which required him to travel to Istanbul. This job involved promoting events like the Louisiana Purchase Exposition and the State Fair of 1904. Lina had a significant allowance from her late father's estate, which was to be paid annually. In 1905, she requested to receive it as a lump sum at Carl’s urging.

In 1906, Hau had to make a second trip to Turkey and suggested that Lina and their young daughter spend time with her mother in Baden Baden while he was away. Although they arranged this, some people were concerned that Hau was becoming too close to Olga. Regardless, Lina, Olga, and Hau went on a trip to Paris. They stayed at the Hotel Regina, which was close to the Louvre, beginning their stay on 25 October 1906.

On 29 October, Josephina received a telegram saying that Olga was ill. She rushed to Paris but found no one sick. 

Carl Hau bought specific items in London, such as a wig, a false beard, a black hat, and a long black coat, possibly including a revolver. He sent a telegram to himself, pretending to be from the Standard Oil Company, saying he needed to go to Berlin. He left Lina in London on November 3, arriving in Frankfurt. He did not go to Berlin but told Lina the meeting was moved to Frankfurt. He discarded the false beard he had from London and bought a new one that matched the color of the wig. On November 6, 1906, he disguised himself and called Mrs. Molitor, asking her to come to the Post Office about a telegram. Despite the maid recognizing his voice, Mrs. Molitor went out with Olga to the Post Office. On the dark streets, they noticed a man following them, and he shot Mrs. Molitor.

Carl fled the scene and got rid of his disguise, returning to his hotel in London. Police later arrested him at the hotel and returned him to Germany. He was imprisoned in Karlsruhe. Lina, his wife, visited him in prison and found out he had spent all her inheritance. She concluded that he killed her mother and, in despair, took a train to Switzerland, where she drowned herself.

The trial took place in July 1907. Carl pleaded not guilty, and the evidence was mainly circumstantial. His father hired a lawyer, Eduard Dietz, to defend him. The prosecutor was Mr. Bleicher, and Judge Eller presided over the trial. Carl admitted to sending the telegrams but insisted he had other reasons. When the verdict of guilty was announced on July 22, it led to a massive riot with around 20,000 people outside the courtroom, which the military had to control.

Carl was sentenced to death, but his wealth allowed him to appeal, and in December, his sentence was changed to life imprisonment. He spent the first 12 years in solitary confinement and was released in September 1924 after 17 years in prison. He later published two books about his crime, violating the terms of his release. A warrant was issued for his re-arrest, and he went into hiding. On February 5, 1926, Carl committed suicide in an abandoned house near Rome.