"When war reared its head, she was invited by Vault-Tec into Vault 92. They claimed the vault would be dedicated to preserving musical talent. "
The true purpose of Vault 92 was to act as a testing ground for the creation of "super soldiers" by way of "subliminal suggestion." By exposing the citizens of the Vault to white noise that contained hidden subconscious messages, the Vault Overseer hoped to create soldiers that could be controlled through a form of hypnosis, thus fulfilling his orders from Vault-Tec. This research was then to be used for a project to create super soldiers who would be completely obedient and fight far more ferociously than normal humans. The Vault's lead researcher Professor Malleus was initially unaware that the overseer intended to use the research team's work to create soldiers. He thought he was researching their musical talents, etc. This is made clear by a series of his recordings you can pick up throughout the Vault.
The recordings state that, although the experiment initially showed great promise, the most promising subject began exhibiting extreme, uncontrollable aggression and tore three people apart before the Vault's security team was forced to subdue him. It took 23 gunshots to finally take him down. Professor Malleus is horrified at this and cannot understand why a resident would act in such an extremely aggressive manner (as far as the doctor is concerned, the suggestions are limited to simple and harmless triggers like obsessive fixing of hair, constant ear scratching etc.). A later log on the Overseer's terminal shows that he intentionally placed a subliminal message in the resident to trigger a violent outburst, as a measure to see whether the command would be obeyed, how much damage he would do, and how much punishment he would be able to survive before Vault Security killed him. He expresses particular delight in the 20+ bullets required to stop the subject, stating that a whole army of soldiers implanted in such a fashion would be unstoppable.
This rage soon manifested in other subjects. One computer terminal contains the diary of one of the inhabitants, Zoe Hammerstein, who went mad because of the white noise. The diary shows her writing (specifically her spelling and grammar) degenerate, until her final entry, where she begs her friends for help in a sentence that is barely comprehensible.
Attempts by the Vault Overseer to contain the situation (such as by programming code words into the subjects' implants in order to stop them) only worked briefly. Professor Malleus, the expert in charge of the white noise experiment, soon lost hope in the project and attempted several times to convince the Overseer, Richard Rubin, to take the situation more seriously and even consider abandoning the Vault in light of the violent and savage behavior of the residents, not realizing what Rubin had done until it was too late. However it seems that Rubin had Professor Malleus killed, based on evidence from a log on his computer terminal.
More than one-half of the Vault's population (according to Professor Malleus's V92-05 audio log) eventually became violently unstable and began slaughtering the rest of their fellow residents. A note titled "Feedback Loop" explains that the survivors yet untouched by experiment made one last push for the escape, possibly explaining why the vault door was left open. The "normal" vault citizens made an attempt to stave off the crazed group, so there are frag mines scattered around the Vault. Sadly, the skeletons of the presumed young lovers Hilda Egglebrecht and Parker Livingsteen can be found locked into the Recording Studio, a place where they once enjoyed accompanying each other greatly, according to notes left by Parker.
The heavy presence of the mirelurks is explained by a computer terminal in the lower, flooded parts of the Vault. Apparently, shortly before the "crazies" incident, there was an issue with one of the walls in that area, which had cracked because of some body of water nearby. The wall was repaired and given some minor reinforcements, but the Chief Engineer of the Vault, Carl Maynard, stated in this terminal that the repairs were only temporary and that a serious approach needed to be discussed. However nothing was done because of the mad inhabitants, and the wall there eventually broke, allowing the mirelurks to gain access to the Vault.