( whole lot wrong with this'en.... But, we are talking russia here where the standard of the living is somewhere between Bangladesh and northern India.
It appears the man with a passport, (BOARDED THE PLANE (4) FOUR DAYS) before he was found dead.

The man was apparently FLYING WITHOUT A TICKET.

Plane made (7) SEVEN FLIGHTS before the maintaince crew noticed blood stains.
There's more, why bother?