Radek grew up with a fairly poor family back in his home country, where he had a brother and a sister named Evzenie.
When he was only a year old, Russia occupied Prague where his family lived. His family chose to leave and they hid in abandoned factories and plants. His father, who worked in a nuclear plant, tried to take one of it's trucks so they could escape to Austria. While getting fuel for the truck, Russians came to arrest them, however a Lithuanian Lieutenant let them go.
When he was young, his brother burnt down his home with one of the lit candles, forcing his family to live in a tent through the cold Czech winter until the house was rebuilt. After growing up, his sister had a son, who, as Radek pointed out "breaks things and smears thing on furniture". He also raised racing pigeons. He became a gifted scientist, and was once offered a job at Masaryk University. However, when he was offered a chance to work in Chernarus, he turned down the offer at the University and joined a team going to the Medical insitute located in Novodimitrovsk , where he was to work under Dr. Stanislav . Zelenka took part in the major breakthrough on biological and chemical developement such as produceing a very potent antibiotic.
Zelenka heard rumors about the virus for years before actually finding out the truth about it, He still dismissed the rumors. After completing his doctorate at Cambridge University, Zelenka took a temporary job at the Chernogorsk hospital where he went learned/picked up very usefull medical skills. Now Zelenka walks the country or Chernarus trying to find documents and his old friends to find a cure and combat the virus which has spread.
Zelenkas mental state has changed since the first infection... the balance of good and evil in his opinion beeing tipped in chernarus. He still aids those who need it but is fiercly patriotic and radical when it comes to defending his morals and homeland.
Rádek has taken to interrogateing prisoners and people with the use of his... not so orthodox medical skills.. to extract information out of them.