Before the Series Edit
Josip Radik was known as a war criminal who led units to destroy villages and the people who lived in them to "ethically purify his country". His total count of casualties when he destroyed the villages was, according to Booth, 232 people, and Booth's army unit was sent in to stop him. When Booth prepared to shoot him from a distance, he was set to go to another village in the next two hours, but he was in the middle of attending his six year old son's birthday party. Booth killed Radik in front of his son, Mark Kovac, after firing at his head from 3,000 feet away. No one at the party knew where the shot came from, "but they knew why it came." Aldo Clemens was with Booth when it happened.
After solving the murder of Devon Marshall, Booth told Brennan about how he had to kill Radik to protect over 100 people when he was sent to Kosovo. After telling Brennan about it, Booth expressed his pain and regret in killing him in front of his own son.
When Aldo Clemens was found dead, Booth and Brennan found an X-Ray of a skull at the abandoned sound studio where Aldo was tortured. Booth later realized that he was the one who made that shot to the person in the X-Ray and that the person in it was Radik. He deduced that Aldo was targeted by someone who was associated with the deceased warlord, and that Clemens sacrificed himself to keep Booth hidden and safe from his abductor.
It was discovered that the person who's out for revenge against Booth is Radik's son; Mark Kovac. After Aldo did not provide any information, Kovac captured and tortured Michael Reiss; another member of Booth's army unit when he was a Ranger, and an old woman named Margaret Kwan. Kovac tortured the old lady until Reiss gave up the name of the sniper who killed his father. He then went on to torture Reiss for a week, keeping him alive when he was going into cardiac arrest with his paramedic's defibrillator. Booth was able to arrest him after he got the proof he needed, but not before Kovac's accomplices, two of Radik's old bodyguards, attacked his children and killed Max Keenan, but not before Max was able to kill both of the hit men in the process.
During the episode, Hodgins comments that he's given Booth a lot of grief for his time as a sniper, but he thinks Booth did the right thing by killing Radik. Camille Saroyan and Jack Hodgins identify the bomber of the Jeffersonian Institute as Jeannine Kovac who is Radik's previously unknown daughter, not Mark Kovac's wife as they previously believed. When confronted by Brennan and Booth for her and her brother's actions, Jeannine taunts that Max's blood is on Booth's hands, and, like her, Brennan now knows what's its like to have her father die in front of her. The episode ended with Mark Kovac dead and Jeannine Kovac imprisoned for the rest of her life.
- Radik was a general from Serbia, but Booth mentioned he was sent to Kosovo to stop him in The Soldier on the Grave, and it's stated that he killed him in Bosnia in The Price for the Past.