Be warned that spoilers follow.Paul Koplin worked for a private detective which Kate Warner had earlier hired to investigate Reza Naiyeer, her brother-in-law to be. Koplin discovered suspicious self-deleting files on Reza's computer but was taken hostage along with Kate by terrorists belonging to Second Wave. Kate was forced to watch his interrogation regarding whether or not anyone else had information. The interrogation techniques used were severe torture.When the terrorists were satisfied that he was telling the truth, they shot and killed him.