Beaumont Children Disappearance, Australia. The three siblings were disappeared on 26th jan 1996 without any leads. Even after 50 years the remains unsolved.
The BLACK KNIGHT SATELLITE. In 1960, a strange satellite was seen in polar orbit of unknown origin. It transmitted radio waves from 1920's to 30's,which were corresponded to a star from Earth 13,000 years ago.
The id of the person or group that created Bitcoin is unknown. Despite many attempts to out the man known as Satoshi Nakamoto.
JACK THE RIPPER, a serial killer in Whitechapel, London in 1888. His victims are prostitute's whose throats were cut prior to abdominal mutations and the removal of internal organs. He claimed the murders by writing a letter by siging as THE RIPPER