Boban Hađiselimović is a hired mercenary, he joined the independence war on the Pro-Russian side. He came from Bosnia, where he lost all in the war during the breakup of Yugoslavia. Shortly after deployment he was captured by the Chernarus forces and locked up. After a few days in the cell, the guards stopped bringing him meals, so he had to escape. Thankfully the wooden doors of the cell were quite wonky, so he broke them open with a few kicks. To his surprise the noise didn't alarm no guards. He ran for his dear life but quickly realized that no one is following.
He headed for the nearest town, where he was greeted by empty streets and devastated buildings. After about a hour of roaming the streets he finally saw a person in the distance. He shouted, the person turned around, started screaming and ran towards Boban, when ''it'' got closer, Boban noticed that it's no human, it's practically a walking corpse. He couldn't believe his eyes and he quickly turned around and ran again. This time towards the woods where he set up a camp to stay for the night.
After some days of exploration he concluded that he is a lone survivor of an ''outbreak'' of a disease of some sort. Or is it all a result of biological warfare? On a couple occasions he thought he saw someone running in the distance, but it was probably just his tired body starting to act in weird ways.
He didn't want to head into unknown on foot, he thought that some sort of help will arrive sooner or later. So he started a new life in a rural part of Chernarus, he was trying to grow enough food not to die of hunger, and he tried to keep the ''visits'' to the city to a bare minimum, since the things seemed to be more concentrated there.