Fritz Heinrich Angerstein was born on January 3, 1891, in Dillenburg, German Reich. He was the seventh of ten children in his family. His father worked as a carpenter and later as a steelworker. He also served as the mayor of Dillenburg. During his childhood, Fritz faced several health problems, including frequent tuberculosis infections. At one point, he even had to have a rib surgically removed.

At the age of 14, Fritz began working as a surveyor. Later, he found employment with the Nassauische Bergbau AG, a mining company. By 1917, he had become the procurator of a limestone mine located in Haiger. This mine was taken over by the van der Zypen company in 1920.

In 1911, Fritz married Käthe Barth, who was a devout Methodist. Their marriage appeared to be happy, and Fritz seemed to be a caring husband. However, Käthe struggled with severe psychiatric issues and fell ill with an unknown intestinal disease in 1920. The weight of managing her illnesses took a toll on Fritz, who was also battling various types of tuberculosis. The couple did not have any children, as Käthe had experienced six miscarriages. Their relationship became strained, particularly with Käthe's mother, who often treated her poorly.

Fritz reported that his mother-in-law reduced Käthe's meals to a simple soup, which was often burnt, leaving Käthe to refuse to eat. Out of frustration, Fritz admitted to using a dog whip on his mother-in-law during an argument about Käthe's treatment. The couple faced many challenges, including Käthe's mental health and their inability to have children.

In 1921, Käthe sent Fritz a letter stating that she could not be the wife he needed because of her health issues. They talked and mutually decided that they could no longer continue living this way. They even contemplated drowning themselves, but a song they heard while walking to the water stopped them.

Later that year, the family moved to Haiger when Fritz received free housing in a villa owned by his employer. Life in the villa included office space for Fritz and his assistants as well as living quarters for his family. Fritz earned a salary of 390 Reichsmark each month. However, he claimed that his employer owed him 90,000 Reichsmark, leading to financial struggles. This trouble led Fritz to embezzle a significant amount of money from his employer, which was later discovered.

On the Friday before the events that would later unfold, Fritz noticed that Käthe had put away a notebook with her last wishes. The following Saturday, he discussed financial matters with his manager, who confronted him about accounting discrepancies. As stress mounted, Fritz's health problems intensified, causing headaches and further complications. 

On the night of November 30 to December 1, 1924, Fritz Angerstein caused damage to a telephone wire and some water pipes. Between 12 and 1 a.m., he was awake while his wife experienced severe heart pain. He wanted to call a doctor, but she stopped him and asked him to fetch her mother. After she returned, Angerstein sat beside his wife as she read him a letter. He then changed the pillow case, which had been stained by her vomiting.

While overhearing a conversation between his wife and mother-in-law about a letter from his brother-in-law stating that he had syphilis, Angerstein became agitated. He recalled his wife had once expressed a wish to die at the same time as him. This pushed him to decide to kill his wife and himself. When his wife fainted, he retrieved a revolver but, when he returned, she regained consciousness and took it from him. She pleaded for forgiveness, but then fainted again. Angerstein then grabbed a hunting dagger and stabbed her 18 times.

After that, he ran downstairs to try to shoot himself, but the guns did not work. He searched for another way to end his life and found a hand-axe. He initially intended to harm himself but rushed back upstairs when he heard his mother-in-law scream. He killed her, claiming later that he was angry about her treatment of his sick wife. He then noticed their maidservant, Minna Stoll, nearby. She attempted to flee but he caught her and struck her over the head with the same axe. Her body was later found burned on the first floor.

Fritz then returned to his bedroom and attacked the bodies of his mother-in-law and wife again, fearing they might awaken. His mother-in-law was still making sounds, prompting him to wash the axe and his hands before resting for a few hours. When his sister-in-law, Ella Barth, came home, he followed her, killed her in the bathroom, and covered her body.

Later that morning, two men came to work at the villa. Angerstein called them into his study one at a time and killed both with the axe. Throughout the day, he also killed two more people: the son of his gardener and a laborer. Fearing they could have witnessed the murders, he silenced them too.

Afterward, Angerstein poured petrol around the ground floor and the first floor of the house. He went out shopping, bought some chocolate bars and a flashlight, and returned home. That evening he ignited the petrol, but the fire did not spread as he expected. In distress, he stabbed himself a number of times, then called for help.

When assistance arrived, he claimed that bandits had invaded the house, killed everyone, and left him for dead. Panic spread among the townspeople over the supposed bandits, and extra police were called in. Investigation into the murders started, and doubts arose about Angerstein's story. Signs showed that rigor mortis had set in on the bodies, contradicting his claims of when the murders occurred.

Evidence, including fingerprints on the weapon and the bodies, pointed to him as the killer. During interrogation, he denied committing the crime, but gave conflicting statements. Eventually, he confessed to killing his family when faced with the evidence.

Fritz Angerstein was charged with multiple crimes, including eight counts of murder. He was sentenced to death after a highly publicized trial. The execution took place by decapitation on November 17, 1925, in a prison courtyard.