The case known as the "Hinterkaifeck Murders" was a single, sextuple murder committed in Waidhofen, Bavaria, Germany on March 31, 1922. The murder was violent, and seemingly done without a motive.

On April 4, 1922, authorities find the deceased bodies of the Gabriel and Gruber family members, as well as their maid, at Hinterkaifeck Farm. Four of them were in the barn, and had their skulls caved in by a mattock. The maid, as well as the youngest son, had been stabbed, and were found in the main home.

Prior to their deaths, the family alleged that a number of things had gone missing from the home, and a different maid alleged that, prior to quitting, she had been hearing strange noises from inside the walls, as well as the attic.

Karl Gabriel was the husband of the widowed Viktoria Gabriel. He had been killed in December 1914 in France by a shell attack in Arras, France. However, his body had not been recovered. After the murders, people began to speculate that Gabriel may never have actually died, but instead had gone back to Hinterkaifeck to kill his and his wife's relatives.

After the end of the Second World War, POWs from the Schrobenhausen region of Bavaria were released from captivity prematurely by a German-speaking Soviet officer, who claimed to be the Hinterkaifeck murderer. However, the men later revised their statements, and thus the credibility of the story was diminished. Furthermore, it is now known that Gabriel did, in fact, die during battle, and is buried in a comrade's grave in St. Laurent-Blangy. His death was confirmed by the Central Prosecution Office, for War Losses and War Graves.

Shortly after the death the death of his first wife, Schlittenbauer was believed to have had a relationship with Viktoria, and fathered Josef. Schlittenbauer came under suspicion by locals early in the investigation, due to his several suspicious actions immediately after the discovery of the bodies. One such action was when Schlittenbauer and two of his friends, Michael and Jakob, were at the farm to investigate the site themselves. Upon disovering the four bodies in the barn, Schlittenbauer entered the main home alone using a key he had obtained, despite not knowing wether the killer was still inside or not.

On another occasion, Schlittenbauer was spotten by local teacher Hans Yblagger visiting the then demolished site of the farm. Schlittenbauer allegedly stated then that the perpetrator's attempt to bury the bodies was unsuccessful, due to the frozen ground because of the winter. This was seen by many as evidence that he had intimate knowledge of the ground because he was the killer, but seeing as he was the neighbor, and was likely familiar with the ground to some degree, he may have made nothing more than an educated guess.

However, Schlittenbauer conducted, and won, several civil claims for slander in 1941 against persons who described him as the "murderer of Hinterkaifeck".

The only reason why the Gump brothers are suspects in this case is due to their sister, Kreszentia Meyer, claiming on her deathbed to Pastor August Rietzl and later to Pastor Anton Hauber, that Adolf and Anton Gump were the murderers of hinterkaifeck.
However, this was later discredited, as all fucking 15 of her siblings stated that this claim was more than likely out of spite for Adolf and Anton Gump. One of the reddits post's sources states that Florentine, one of those siblings, stated that Kreszentia Meyer was prone to criticizing the siblings, but especially Anton Gump.

In 1971, a woman named Therese T. reported that when she was 12 years old, her mother had a visit from the mother of the "two murderers of Hinterkaifeck" (taken directly from the reddit post). During the conversation, the names of the persons who were said to have committed the crime were mentioned: Karl Schreier and Andreas Schreier.

Therese T. also mentioned that Mrs. Schreier later committed suicide, by building a pyre in her kitchen, dousing everything in kerosene, and lighting herself on fire.

Furthermore, an article from the New Free People's Newspaper from August 4th, 1922, stated that: "After the [murders], [Karl and Andreas Schreier] could not hide the traces of their crime from their mother, who finally wanted to ease her opressed conscience of the confessional knowledge. As a result, she informed the neighbor of the terrible deed of her sons, which finally brought about the gend" (I have absolutely no clue what "gend" means). It also reads: "The two brothers, widely known and feared as violent people, were near Waidhofen at the time busy pulling wood from the forest and drove past Hinterkaifeck every day so that they could know the conditions there exactly."

At first, all of this sounds pretty damning, but there is no real evidence to uphold this. The only sources I could find that seem convincing are the reddit post, and the Wikipedia article.

The maid, Kreszenz Rieger, the one who quit six months prior to the murders accused the Bichler brothers along with Siegl of being the killers.

Anton Bichler helped with the potato harvest at Hinterkaifeck, and thus would know the premises. Rieger stated that Anton talked to her often about the family, and allegedly stated that the family had to die. Rieger also allegedly emphasized in her interrogation that the farm dog barked at everyone but Anton.

Anton Bichler and Rieger were in a "love affair", and he would often come to her window at night. However, one night, instead of Anton, it was someone different, judged by the different voice, and Rieger suspected it to be Karl Bichler. This unknown person asked if Viktoria Gabriel was with Andreas Gruber that night, but left when Rieger refused to answer.

The reason Siegl is accused is because he had allegedly broken into the home in November 1920, which Siegl denies doing. He did, however, claim to have carved the handle of the murder weapon, and knew where the mattock was kept.

More brothers I swear to god-

Andreas and Josef Thaler were suspected by Kreszenz Rieger, mostly because on a particular night, she saw Josef Thaler, along with another man (presumably Andreas Thaler), looked at the machine house, and "turned their eyes upwards".

The Thaler brothers also allegedly committed various break-ins prior, which I guess made Rieger suspect them, but I'm not sure.

Most people at the time suspected that Lorenz Schlittenbauer was behind the murder. However, he sued everyone who said so, and won each time.
Since Schlittenbauer is now dead, we don't have to fear him suing us anymore (except maybe his relatives).
I believe that he was the killer for two reasons:

1. He had an unwavering hatred towards Andreas Gruber.
2. He was the unofficial husband of Viktoria Gabriel, and he'd inherit the farm if the family died.

I'll elaborate: Schlittenbauer hated Gruber because Gruber hated Schlittenbauer, and because Schlittenbauer likely knew of the incestious relationship between Gruber his daughter, Viktoria Gabriel (No, I'm not kidding.). Furthermore, I also think that Schlittenbauer had an accomplice, for two reasons:

1. Police statements indicate that things were done in the house that could only have been done by two or more persons*.
2. Mere hours after the murders, two people were seen somewhere on the premises.