1. Two insane sisters shared a temporary psychosis
Ursula and Sabina Eriksson are Swedish twins who supposedly went totally fucking batshit crazy together for roughly 72 hours. There’s footage (and subsequently a whole documentary) of them repeatedly throwing themselves into oncoming traffic and getting hit/run over by multiple cars and even an 18-wheeler. When police arrived to sort things out, they became extremely violent like cornered animals, eventually leading them to need restraints just to administer medical attention.
One was charged with assaulting a police officer when she was released from the hospital (a span of a few hours), to which she responded apathetically or even cheerfully. After something like 2 days in a holding cell, she plead guilty and was sentenced 1 day (which she already served) and was released.
Something like a day later, some guy found her wandering around the street looking lost/confused. He invited her in to let her use his phone and try to track down the sister (who was still in the hospital, I believe), and she apparently stabbed the guy 3-4 times in the chest, killing him.
I say “apparently” because all the evidence suggested that it was her, but she never actually gave her account of what happened. She answered every question with “no comment” from the moment of arrest throughout the trial.
To top the whole thing off, doctors at the trial declared that she was insane when she committed the crime, but that she was now completely sane, and was not currently a risk to the public. The judge wanted to give her an indefinite sentence, so they would have more time to evaluate the possibility of it happening again. The law, however, required that he give her a definite sentence, since she was declared to not currently be a risk to the public. He sentenced her to 5 years in prison.
She was released in 2011 and has essentially fallen of the map since then. We know that she kept in contact with her twin through her sentence, and that they likely reunited upon release, somewhere in America.
2. Poisonous blobs fell from the sky
The Oakville Blobs. Gelatinous blobs fell from the sky in Oakville, WA in the early 90’s that made people sick and killed some animals. After testing it was shown to contain human white blood cells.
3. A group of boys went missing for twenty years
A mysterious case from South Korea that had never been solved called the Frog Boys about a group of boys (5) gone missing without their corpse, remaining, nor any evidence found for about 20 years. Even soon after a massive police search in the whole area foot-by-foot, nothing was found. However, 20 years later, their remaining have been spotted and discovered just right near their home area, which have already been searched for thoroughly. During this period, there were multiple theories and conspiracies. One professor also personally tried playing detective and accused one of the parents for being the offender with some logical contents and accusations.